A fuel cell apparatus corresponds to a first slave apparatus among a plurality of fuel cell apparatuses that includes a master apparatus and slave apparatuses including the first slave apparatus and a second slave apparatus. The first slave apparatus includes a cell stack, a communication unit, and a controller. The communication unit communicably connects to the master apparatus and the second slave apparatus. The controller controls the cell stack on the basis of control information acquired from the master apparatus. The controller transmits a master candidacy message indicating assumption by proxy of functionality of the master apparatus to the second slave apparatus from the communication unit when the controller detects that the master apparatus has lost functionality.