Provided is a liquid pressure device having no dead band in generation of force and causing no contamination, the liquid pressure device including a bottom cap and a head cap welded to an outer tube, and a rod guide fastened to the head cap, and one end of a pipe is fit in the bottom cap and the other end of the pipe is fit in the rod guide, and the bottom cap and the rod guide sandwich a cylinder. Accordingly, the liquid pressure device of the present invention can add shaft force to the cylinder while supporting the pipe, an inside of which is isolated from a tank, by the bottom cap and the rod guide, and does not need to braze the pipe to the bottom cap. Therefore, the liquid pressure device of the present invention has no dead band in generation of force and causes no contamination.