A circuit unit of a drive device includes a circuit board on which electronic components are mounted. The circuit board extends outward beyond a motor region that overlaps with a motor unit. A housing includes a housing main body and a cover. The housing main body has a motor housing portion, which receives the motor unit, and a circuit housing portion, which receives the circuit unit and is formed integrally in one-piece with the motor housing portion. The cover covers an opening of the housing main body. At least one of the housing main body and the cover is configured to receive heat generated from the circuit unit. The housing has heat dissipation portions. The heat dissipation portions include peripheral-wall heat dissipation portions, each of which projects from a peripheral wall portion of the housing that surrounds an outer periphery of the circuit board.