The invention relates to a fuel cell device with a pressing device (3) for pressing a fuel cell stack of the fuel cell device, as well as a pressing device (3) for pressing the fuel cell stack. In order to be able to press the fuel cell stack as needed, the invention provides that the pressing device (3) have a pretensioning unit (9a) with an adjusting element (12) and a supporting element (13), wherein contact surfaces (15, 16) of the adjusting element (12) and of the supporting element (13) extend obliquely to the pressing direction (P).