An electric actuator includes a motor and a deceleration mechanism. The motor has a motor case having a first opening end surface. The deceleration mechanism has a deceleration mechanism case having a second opening end surface. The motor case and the deceleration mechanism case are connected via a sealing member. The first opening end surface has a first end surface body part and a first end surface protrusion part. The second opening end surface has a second end surface body part and a second end surface protrusion part. The sealing member has a body part sealing part and a protrusion part sealing part. The protrusion part sealing part has an axial-direction protrusion that faces a side surface of the motor case in the first end surface protrusion part or a side surface of the deceleration mechanism case in the second end surface protrusion part in a circumferential direction.