A cylinder of the invention can precisely send out a piston rod 3 into four different positions and comprises: a spring receiving member 14 placed coaxially with piston rod 3 in a piston room (I-II) of a cylinder tube 2 so that the movement of spring receiving member 14 is limited by one end of the piston room; a first spring member 15 to separate the spring receiving member from the piston; a stopper 8 formed on piston rod 3 to limit spring receiving member 14 from moving in the opposite direction to piston 4, a hollow 9 formed on the periphery of piston rod 3 at farther position from piston 4 than stopper 8; and a stop pin 11 installed in the cylinder tube to be pressed in the direction of hollow 9 by a second spring member 12 to engage with hollow 9, wherein the movable length of piston rod 9 while stop pin 11 is engaged with hollow 9 is larger than movable distance of spring receiving member 14 from the piston. A load port and a production system of this invention are constructed using the cylinder.