A seat driving device includes a rotary motor having a rotary shaft, operation members, and clutch mechanisms. The operation members are separately arranged to respectively correspond to position adjustment mechanisms. The clutch mechanisms are separately arranged to respectively correspond to the position adjustment mechanisms. When any one of the operation members is operated, each clutch mechanism selectively connects the corresponding position adjustment mechanism to the rotary motor. In response to operation of any one of the operation members, the rotary motor is energized with the polarity corresponding to the operation direction of the operation member. Each clutch mechanism is arranged with respect to the rotary motor such that the axis of the clutch mechanism is parallel with the axis of the rotary shaft.