An object of the present disclosure is to provide a method for manufacturing a fuel cell that ensures developing a high adhesive strength to a separator. One aspect of an embodiment is a method for manufacturing a fuel cell where a pair of separators are mutually bonded with a sealing member. The sealing member includes a thermoplastic resin containing a crystalline polymer as an adhesive layer. The method for manufacturing the fuel cell includes: preparing a stack structure in which the sealing member is disposed between the pair of separators; heating the stack structure at a melting point or higher of the thermoplastic resin; after the heating, holding the stack structure in a temperature range of ±10° C. of a crystallization temperature of the thermoplastic resin to promote a crystallization of the thermoplastic resin; and after the holding, further cooling the stack structure.