Abstract: In a wafer transfer system wherein a wafer transfer robot linearly reciprocates by a linear motor, dust is prevented from adhering to a wafer. A fixed base 9, on which the secondary side 11 of a linear motor M for linearly reciprocating a wafer transfer robot R is mounted, is mounted on the system body 1 of a wafer transfer system A in lateral directions and in vertical directions, so that dust dropping in accordance with the flow of clean air K from a clean air supply system 4 is directly sucked into an exhaust fan 5, which is provided on the bottom portion 1c of the system body 1, to be exhausted without being deposited on the top face of the fixed base 9 and the secondary side 11.

Abstract: An attaching and removing unit of a lid for a wafer carrier according to the invention includes: a lid holding plate that can move forward and backward relatively to a lid for a wafer carrier provided with a lock unit having a keyhole exposed outside, on a side of the keyhole; a driver for causing the lid holding plate to move forward and backward; and a key element protruding from the lid holding plate on a side of the lid in a pivotable manner, the key element disposed opposite the keyhole in a direction of the forward and backward movement. The lock unit is adapted to be locked and unlocked by the key element pivoting in the keyhole. In a locked state, the key element can be inserted into and released from the keyhole, and in an unlocked state, the key element is engaged with and can not be released from the keyhole, while the lid holding plate holds the lid. The lid holding plate is provided with a lid-detecting unit for detecting whether the lid holding plate is holding the lid or not.