To provide a hydraulic buffer equipped with a piston part structure improvable for slide durability of a seal member and chalk effect, and difficult to be affected by the influence of temperature change.

In a hydraulic buffer wherein a piston rod 3 is inserted into a cylinder 1 movably via a piston 2, the piston 2 demarcates the cylinder 1 into rod and antirod side oil chambers A and B, an extending side port 4 and a pressure side port for communicating two oil chambers are provided in the piston 2, an extending side valve 5 is provided opening/closing freely on the outlet end of the port 4, and a pressure side valve 6 is provided opening/closing freely on the outlet end of the pressure side port; the following are provided: a guide piston 8 coaxial with the piston 2 on the rod 3, a seal material 9 slidably contacting with the cylinder 1 on the outer periphery of the piston 2, an oil hole 11 on the piston 8, and also a bearing material 10 for slidably contacting with the cylinder 1 on the outer periphery.