A robot arm includes a first member, and a second member translating along an axis located in the first member or rotating around the axis, and the first member has a base, a drive unit generating a drive force, a joint portion having a driven pulley and transmitting the drive force to the second member, a belt transmitting the drive force generated by the drive unit to the driven pulley, a sensor provided in a position overlapping with a region surrounded by the driven pulley and the belt in a plan view along the axis and detecting vibration, a wire routed to the region and coupled to the sensor, and a supporting member provided in the region and supporting the wire.