A compression apparatus includes a stack of electrochemical cells each including an anode, a cathode, and an electrolyte membrane interposed therebetween, a pair of insulating plates disposed at respective ends of the stack in a stacking direction, a pair of end plates disposed on outside surfaces of the respective insulating plates, and a voltage applicator that applies a voltage between the anode and the cathode. The end plate having the cathode gas channel includes a first region that includes an outer peripheral surface of the cathode gas channel and is composed of a first steel material and a second region other than the first region which is composed of a second steel material. The first steel material has higher hydrogen embrittlement resistance than the second steel material, and the second steel material has higher stiffness than the first steel material.