A servo motor controller comprises: a position command generation unit; a position detection unit; a position control unit that generates a velocity command for position control based on a position command and a position FB; a force command generation unit that generates a force command for instructing force to be applied to a subject by a driving target; a force detection unit; a force control unit that generates a velocity command for force control based on the force command and a force FB; a selection unit that selects one of the position control and the force control; and a storage unit that stores a force threshold. The selection unit selects one of the velocity commands for the position control and the force control of a smaller value. If the force FB is smaller than the force threshold, the selection unit selects the velocity command for the position control.