To facilitate manufacture of a pitch varying mechanism for substrate transfer mechanism while lowering the price and shortening the schedule of delivery.

A rod guide 31 is provided with a plurality of arm blocks 37, 39, 45 and 47 slidingly and a link arm 35 is fitted to the output shaft 34 of a rotary actuator 33 while intersecting the guide. The link arm 35 is linked with the arm blocks 37, 39, 45 and 47 through a plurality of links 60, 61, 62 and 63. The arm blocks 37, 39, 45 and 47 are fixed with a substrate carrying plate and when the link arm 35 is turned by a rotary actuator 33 through an output shaft 34, the arm blocks 37, 39, 45 and 47 are moved up and clown along the guide 31.