Slide valve

This slide valve comprises: a valve box having a hollow section and a first opening and a second opening that are provided so as to face each other, with the hollow part therebetween, and serve as communicating flow paths; a neutral valve body that is positioned inside the hollow section of the valve box and is capable of blocking the first opening; a rotating shaft that rotates the neutral valve body between a valve blocking position where the neutral valve body is put in a blocking state with respect to the first opening, and a valve unblocking position where the neutral valve body is put in an unblocking state retracted from the first opening; a rotating device comprising a rack and pinion for rotating the rotating shaft, and a rotating air cylinder for driving the rack and pinion; an unblocking driving part comprising an unblocking air cylinder for performing an operation that releases the blocking of the neutral valve body; and a sequence circuit that is capable of operating, in sequence, the operation f