A culture apparatus which is capable of shortening sterilization time includes a gas concentration measuring sensor, pipes connected to a gas concentration measuring device and every corner of a cultivating chamber, and a sterilizing gas generator that supplies sterilizing gas into a cultivating chamber and atomizes a sterilizer solution (oxygenated water) by means of an ultrasonic vibrator. The culture apparatus further includes an ultraviolet lamp that irradiates gas in the cultivating chamber, a freely opening/closing door, a door-locking device, and a controller for controlling the locking device to prevent the door from being opened from start of the sterilization process to end of the decomposition process.