A fuel cell includes a plurality of power generation cells each having a first separator. The separator has a fuel gas flow field. A fuel gas supply passage extends through one corner of the power generation cell in the stacking direction, a fuel gas flowing through the fuel gas supply passage into a fuel gas flow field. An inlet buffer is provided upstream of the fuel gas flow field. The fuel gas supply passage and the inlet buffer are connected by a plurality of inlet connection grooves. The inlet connection grooves are inclined from a direction perpendicular to a wall surface of the fuel gas supply passage toward the center of the fuel gas flow field.