PURPOSE: To obtain a conveying apparatus capable of easy lot management in cassette unit while the throughput of a thin film processing apparatus in a mass-production line of a semiconductor factory is kept high, by constituting said apparatus of two load lock chambers, a rotary arm type conveying robot, and two cassette stacker which are respectively specified.

CONSTITUTION: A semiconductor wafer air conveying apparatus constituted by using a cassette striker, load lock chambers, and a rotary arm type conveying robot is provided with the following; a loading side load lock chamber 19 into which wafers before processed are sent, an unloading side load lock chamber 20 from which processed wafers are taken out, a rotary arm type conveying robot 21 capable of 360° rotation, whose rotary arm axis is positioned at a vertex of an isosceles triangel whose both ends of the base are at the positions of both load locks 19, 20, and two cassette stackers 16, 15 capable of vertical movement which face the respective load lock chambers 19, 20 via the above rotary arm axis position. On the cassettes 3, 6 on which wafers before processed have been mounted, the same wafers after processing are mounted.