A respiration control apparatus connected to a controlled body includes a respiration circuit having an inhalation circuit and an exhalation circuit. The inhalation circuit includes a first solenoid-operated valve and a first check valve. The exhalation circuit includes a vent valve, a dehumidifying chamber, a pressure detector, a second check valve, and a second solenoid-operated valve. A central processor closes the first solenoid-operated valve and the second solenoid-operated valve based on a respiration control signal supplied from a synchronizing signal output control device, disconnecting the respiratory system of the controlled body from the outside of the respiration control apparatus.