Provided is a fuel cell stack capable of suppressing damage to a seal member and suppressing leakage of a reaction gas to the outside of a casing or entry of water from the outside of the casing for a long period of time. The fuel cell stack includes a pair of end plates and holds a laminate from two sides in a direction, a casing which houses the laminate and has connection bars extended between the pair of end plates, a fastening member inserted into an end plate side mounting hole and a connection bar side mounting hole, and chamfered parts formed in an end plate side small diameter part of the end plate side mounting hole. A chamfer angle between an inner surface of the outer chamfered part and the direction is larger than a chamfer angle between an inner surface of the inner chamfered part and the direction.