A rectangular gate valve having an improved driving action is disclosed. The rectangular gate valve of the present invention includes a sealing member, which opens or closes a wafer moving passage, a main shaft, which is coupled to the sealing member and has a guide member, and a housing bracket, which has a first guide slot, into which the guide member is inserted. The gate valve further includes a valve drive unit, which is provided in the housing bracket and has an air cylinder, a piston, a piston shaft, a moving unit and a connection link. The gate valve further includes a guide bracket, which has a vertical bracket, a second guide slot and a horizontal bracket. The gate valve further includes a guide link, which is moved along the second guide slot to guide movement of the main shaft.