A caliper brake apparatus includes a brake lining that advances/retreats relative to a caliper main body supported on a vehicle body and can apply a frictional force by slidingly contacting a disc, an anchor pin that supports a guide plate supporting the brake lining on the caliper main body such that it can freely advance/retreat, a piston that advances/retreats relative to the caliper main body and can press the brake lining via the guide plate, a diaphragm that abuts a rear surface of the piston and defines a pressure chamber within the caliper main body and elastically deforms due to pressure of compressed air within the pressure chamber so as to move the piston, and a piston plate that supports the piston on the anchor pin such that the piston can freely slide. The piston includes a plurality of thermal insulation members whose distal ends protrude toward the guide plate.