A motor for driving a movable body, the motor comprising: a field magnet holder that holds a field magnet (28a, 28b); a coil holder rotatable relative to the field magnet holder; a conducting coil (101a, 101b, 102a, 102b, 103a, 103b, 104a, 104b, 105a, 105b, 106a, 106b, 107a, 107b, 108a, 108b, 109a, 109b, 110a, 110b) that is wound on the coil holder and generates a rotational force between the coil holder and the field magnet holder when a current flows in the conducting coil (101a, 101b, 102a, 102b, 103a, 103b, 104a, 104b, 105a, 105b, 106a, 106b, 107a, 107b, 108a, 108b, 109a, 109b, 110a, 110b); a brake coil (111a, 111b) that is wound on the coil holder, where an electromotive force for generating magnetic field that suppresses relative rotation between the coil holder and the field magnet holder is induced at both ends of the brake coil (111a, 111b) when a current flows in the conducting coil (101a, 101b, 102a, 102b, 103a, 103b, 104a, 104b, 105a, 105b, 106a, 106b, 107a, 107b, 108a, 108b, 109a, 109b, 110a, 110b); characterized by further comprising: a switch unit that is electrically interposed between the both ends of the brake coil (111a, 111b); and a state setting unit configured to set the switch unit to be in a closed state when the rotation number of a shaft of the motor acquired through a rotation-number acquiring unit is larger than a threshold and to set the switch unit to be in an opened state when the rotation number of the shaft of the motor acquired through the rotation-number acquiring unit is smaller than the threshold, wherein the brake circuit is closed in the closed state of the switch unit and the brake circuit is partially opened in the open state of the switch unit. a field magnet holder that holds a field magnet (28a, 28b); a coil holder rotatable relative to the field magnet holder; a conducting coil (101a, 101b, 102a, 102b, 103a, 103b, 104a, 104b, 105a, 105b, 106a, 106b, 107a, 107b, 108a, 108b, 109a, 109b, 110a, 110b) that is wound on the coil holder and generates a rotational force between the coil holder and the field magnet holder when a current flows in the conducting coil (101a, 101b, 102a, 102b, 103a, 103b, 104a, 104b, 105a, 105b, 106a, 106b, 107a, 107b, 108a, 108b, 109a, 109b, 110a, 110b); a brake coil (111a, 111b) that is wound on the coil holder, where an electromotive force for generating magnetic field that suppresses relative rotation between the coil holder and the field magnet holder is induced at both ends of the brake coil (111a, 111b) when a current flows in the conducting coil (101a, 101b, 102a, 102b, 103a, 103b, 104a, 104b, 105a, 105b, 106a, 106b, 107a, 107b, 108a, 108b, 109a, 109b, 110a, 110b); characterized by further comprising: a switch unit that is electrically interposed between the both ends of the brake coil (111a, 111b); and a state setting unit configured to set the switch unit to be in a closed state when the rotation number of a shaft of the motor acquired through a rotation-number acquiring unit is larger than a threshold and to set the switch unit to be in an opened state when the rotation number of the shaft of the motor acquired through the rotation-number acquiring unit is smaller than the threshold, wherein the brake circuit is closed in the closed state of the switch unit and the brake circuit is partially opened in the open state of the switch unit. a switch unit that is electrically interposed between the both ends of the brake coil (111a, 111b); and a state setting unit configured to set the switch unit to be in a closed state when the rotation number of a shaft of the motor acquired through a rotation-number acquiring unit is larger than a threshold and to set the switch unit to be in an opened state when the rotation number of the shaft of the motor acquired through the rotation-number acquiring unit is smaller than the threshold, wherein the brake circuit is closed in the closed state of the switch unit and the brake circuit is partially opened in the open state of the switch unit.