Nobisuke Nobi, known in Italian as the father of Nobita, is the head of the Nobi household and a recurring presence in the everyday life of the family. He is married to Tamako, with whom he has an only son named Nobita, and he gradually comes to treat the robot cat Doraemon, who lives with the family, as one of his own children. He works as a salaryman at an ordinary company in Tokyo and commutes by train every day, leaving home very early in the morning and returning in the evening toward the hour when the family is usually gathered. Because of these long working hours, he appears in the series less frequently than other members of the household, and his job sometimes forces him to miss planned family trips or leaves him unable to sleep. His age is not fixed consistently across the various stories, but he is generally presented as a man in his early forties.

His upbringing shaped much of his character. He grew up in the same house where the Nobi family still lives, experienced poverty in his youth, and was evacuated to a mountain community during the wartime bombing. As a schoolboy he was not a good student and often received zero on tests, he was somewhat clumsy and lazy, and he was even bullied by boys who were ancestors of Gian and Suneo, which mirrors the situation his own son later faces. Despite his poor academic record, he had a genuine talent for drawing. He dreamed of becoming a painter, won a national school art contest as a child, and as a middle school student studied painting under a struggling artist who eventually became famous. As a young man he was offered the chance to study abroad at the expense of a wealthy family, on the condition that he marry their daughter, but he refused because he believed that the path of life must be carved out by oneself. His dream of becoming a professional painter was never realized, though he still paints occasionally. It was shortly after this decision that he met Tamako, when he accidentally collided with her in the street while running in his student uniform; he later chased after her to return the commuter pass she had dropped, and that encounter led to their relationship. Their wedding anniversary is November 3, and they have been married for twelve years.

By nature, Nobisuke is warm and easygoing, rarely losing his temper and generally avoiding direct conflict. Unlike his wife, he seldom scolds Nobita and prefers gentle advice over harsh lectures. When he does reprimand his son, it is usually not about school grades but about Nobita's tendency to stay indoors and depend on others; he encourages the boy to go outside, play, and live his own adventures. He rarely contradicts Tamako and usually adapts to her decisions even when he is not entirely in agreement, and he sometimes keeps a secret stash of money hidden in a rain boot. He is slightly clumsy, forgetful, and absent-minded, hopeless at cooking and household repairs, and weak-willed when it comes to his own resolutions, such as dieting. His career is one of his main concerns in the stories: he hopes to be promoted or at least recognized by his superiors, and on several occasions this happens thanks to the intervention of Doraemon. He is a diligent and reliable provider who takes pride in supporting his family, even though he is not ambitious or remarkably successful.

His hobbies and personal habits are distinctive. He likes sitting in the living room reading the newspaper, drinking melon liquor, which is his favorite beverage, smoking a pipe or cigarettes, often in secret because Tamako tries to make him quit, and watching baseball games, supporting the Yomiuri Giants and becoming irritated when they lose. He has attempted to quit smoking many times without success. He is passionate about fishing, though his skill is mediocre at best, and he enjoys golf despite playing poorly; he is also something of a rain man, because it always seems to rain when he goes golfing. He has failed his driving test repeatedly and dislikes cars because of this, although he can drive competently in practice situations. He likes music and once bought an expensive stereo system, and he has also been known to play pachinko, buy lottery tickets, and play mahjong with acquaintances. From time to time he returns home drunk after social gatherings with colleagues, and in one incident he nearly lost his monthly salary as a result. As a child he had a great fascination with dinosaurs and searched for fossils near his home without success. In his school days he also played as a pitcher in student baseball.

Within the story, Nobisuke serves as a stabilizing adult presence and provides the perspective of the parents' generation. He appears mostly at home in the evenings, reading, smoking, or watching television, and in episodes centered on his work, his hobbies, or his past. Time-travel stories reveal important moments of his life, including his proposal to Tamako near the fountain of a large park, his presence at the hospital when Nobita was born, and an encounter during his wartime evacuation when Nobita, disguised as a girl, gave him food. He fully accepts Doraemon as a member of the family; when Tamako once referred to the household as three people, he corrected her by insisting that they were four, and he keeps a photograph of the whole family, including Doraemon, on his desk at work.

His key relationships define his role. With Nobita he is patient, supportive, and sympathetic, often arriving home to soften Tamako's anger toward the boy. With Tamako he is accommodating and rarely argumentative, even when he quietly disagrees with her. With Doraemon he is accepting and treats the robot as an equal family member. His own father was extremely strict and frightening, and this memory surfaces in an episode where, after dreaming of his father's words, Nobisuke briefly attempts to raise Nobita with the same harsh discipline, only to abandon the approach when it goes too far. His mother, to whom young Nobita was deeply attached, died when Nobita was in kindergarten, and his father died years before Nobita was born. He has a younger brother named Nobiru who lives in the United States and occasionally visits the family. In the future, when Nobita is about to marry Shizuka, Nobisuke appears even calmer than in the present, trusting that his son, despite his flaws, will become a good family man; by that time he is noticeably balder but has never stopped smoking. When Nobita later has a son of his own, he names the boy Nobisuke in honor of his father.

Because the series does not follow a continuous timeline, Nobisuke does not develop gradually across seasons, but individual episodes give him depth by exploring his youth, his youthful dream of becoming a painter, his courtship of Tamako, his wartime childhood, and his old age. These stories show a man who gave up his artistic ambition for the sake of principle, made peace with an ordinary but honest life, and found fulfillment in his family. His most notable ability is painting, in which he has genuine talent and early recognition, but he is also capable of surprising physical effort when it matters, such as sprinting to the hospital when Nobita was born. His forgetfulness, weakness for alcohol and tobacco, poor driving record, and gentle indecisiveness are presented as mild human flaws that make him a realistic and sympathetic figure within the family.