PURPOSE: To prevent that a slip is caused by a method wherein, when a wafer is transferred, the peripheral edge side of the wafer is separated form the bottom part of a wafer holding groove so that the difference of thermal expansion can be absorbed sufficiently.

CONSTITUTION: A wafer boat turning apparatus is provided with a boat support part 18 which supports both ends of a wafer boat 10, with a vertical turning and driving mechanism 22 which turns it inside a vertical plane, with a vertical driving mechanism 26 which moves the boat support part to the up-and-down direction and with a horizontal turning and driving mechanism which turns the boat support part inside a horizontal plane. In the turning apparatus, a wafer bearing member 52 is formed at the boat support part along its lengthwise direction. Thereby, when the wafer boat which has been laid in a horizontal state is lifted up, a wafer W housed in it is lifted up slightly and the wafer boat is erected. Thereby, the difference of expansion caused between the wafer and the wafer boat in a heat treatment can be absorbed easily.