To provide a reciprocating machine causing little tranfer of heat generated around a piston during an operation to a piston pin for improving thermal insulation effect.

In the reciprocating machine including a cylinder 1, the piston 3 slidably inserted in the cylinder 1, insertion holes 3a, 3b provided to penetrate the piston 3, the piston pin 4 inserted into the insertion holes 3a, 3b, a connecting rod 5 rotatably provided to the piston pin 4, and insulating materials 9a, 9b provided between the piston pin 4 and the insertion holes 3a, 3b of the piston 3, a space is provided between side faces of the insertion holes 3a, 3b, and the piston 4.