A heat insulating structure in a piston type compressor includes a heat insulating member. The piston type compressor includes a cylinder block and a cover housing connected to the cylinder block, a piston is accommodated in a cylinder bore defined in the cylinder block to define a compression chamber. A suction pressure region and a discharge pressure region are defined in the cover housing. The piston is reciprocated in the cylinder bore in accordance with rotation of a rotary shaft so that refrigerant gas is drawn from the suction pressure region to the compression chamber and discharged from the compression chamber to the discharge pressure region. The heat insulating member has a predetermined shape and is located in the cylinder block. The heat insulating member has an inner peripheral surface that defines the cylinder bore.