A CVD apparatus includes a vertical boat extending in a vertical direction and capable of holding plural substrates in a horizontal state such that the substrates are aligned in the vertical direction, an inner tube extending in the vertical direction and provided so as to surround the boat laterally, an outer tube surrounding the inner tube laterally from outside, the outer tube further covering a top part of the inner tube, a flange holding the inner tube and outer tube at respective bottom ends thereof, gas introducing nozzles provided on a flange sidewall at two locations thereof, the gas introducing nozzles introducing gases from outside to an interior of the inner tube at respective gas ejection ports, and a gas evacuation part evacuating a gas in the outer tube to outside thereof, wherein there is provided a guide part in the vicinity of the gas ejection ports of the gas introducing nozzles such that the gases ejected from the respective gas ejection ports are caused to flow generally parallel to a bottom surface of the flange along an inner surface of the flange sidewall.