A reaction force output device that outputs a reaction force to an operation unit, comprising: a motor as a drive source configured to create the reaction force; a reaction force transmission unit configured to transmit the reaction force to the operation unit; and a clutch mechanism disposed between the motor and the reaction force transmission unit and configured to set the motor and the reaction force transmission unit to a disengaged state or an engaged state depending on a driving state of the motor, wherein the clutch mechanism includes: a first rotary member connected to a rotation shaft side of the motor in the path; a second rotary member disposed coaxially with the first rotary member to relatively rotate and connected to the reaction force transmission unit side in the path; and a holder block disposed coaxially with the first rotary member and the second rotary member to relatively rotate between the first rotary member and the second rotary member and configured to hold a clutch pin to move forward and backward, the second rotary member includes a clutch engagement portion configured to come in contact with a tip of the clutch pin protruding from the holder block to transmit power, and the clutch pin is biased in a backward moving direction by a return spring and a base end of the clutch pin comes in contact with the first rotary member to be pressed in a protruding direction when the first rotary member is rotated by the motor. a motor as a drive source configured to create the reaction force; a reaction force transmission unit configured to transmit the reaction force to the operation unit; and a clutch mechanism disposed between the motor and the reaction force transmission unit and configured to set the motor and the reaction force transmission unit to a disengaged state or an engaged state depending on a driving state of the motor, wherein the clutch mechanism includes: a first rotary member connected to a rotation shaft side of the motor in the path; a second rotary member disposed coaxially with the first rotary member to relatively rotate and connected to the reaction force transmission unit side in the path; and a holder block disposed coaxially with the first rotary member and the second rotary member to relatively rotate between the first rotary member and the second rotary member and configured to hold a clutch pin to move forward and backward, a first rotary member connected to a rotation shaft side of the motor in the path; a second rotary member disposed coaxially with the first rotary member to relatively rotate and connected to the reaction force transmission unit side in the path; and a holder block disposed coaxially with the first rotary member and the second rotary member to relatively rotate between the first rotary member and the second rotary member and configured to hold a clutch pin to move forward and backward, the second rotary member includes a clutch engagement portion configured to come in contact with a tip of the clutch pin protruding from the holder block to transmit power, and the clutch pin is biased in a backward moving direction by a return spring and a base end of the clutch pin comes in contact with the first rotary member to be pressed in a protruding direction when the first rotary member is rotated by the motor.