To provide a quick-grip cylinder which is the result of developing the assembling method of a capless quick-grip cylinder, is simple practically and of a low cost, and can lift up numerous loads in a reliable operation.

In the manufacturing and assembling method of a capless quick- grip cylinder having a feeding nipple which has the role to fix a work whose clamping force is to grip a clamp spring, and a carrier plate on a machine tool generated by a hydraulic piston to overcome the clamping force of the clamp spring operating to release, the individual function unit of the capless quick-grip cylinder 1 is assembled from the piston side, that is, from the side to compose the bottom side of the quick-grip cylinder 1. In such a quick-grip cylinder, the function part arranged inside of the cylinder is fixed in an adiquate position by a replaceable bottom 35 fixed to the bottom part of the quick-grip cylinder allowable to release, and thereby, the quick-grip cylinder is closed.