A motor actuator includes a housing, and a plurality of output mechanisms accommodated in the housing. The housing includes a fastening unit that fastens a first case and a second case. Each of the plurality of output mechanisms includes a motor and a plurality of deceleration gears. The motor is supported by the housing. A final state deceleration gear is rotatably supported by the housing. The fastening unit is arranged in a first fastening unit formation range. The first fastening unit formation range is a range formed by connecting contours of a plurality of motors and contours of a plurality of final state deceleration gears, and is a range that surrounds the plurality of motors and the plurality of final stage deceleration gears.