A producing method of a fuel cell stack includes a transfer robot configured to clamp and to transfer a membrane electrode assembly (MEA) and a gas diffusion layer (GDL) component. A feeding testing unit is configured to check a stacked status of the MEA and the GDL component while the MEA and the GDL component are transferred and stacked by the transfer robot. A control unit is configured to receive a signal of the feeding test unit and to transmit an error signal when it is determined that the MEA and the GDL component are erroneously stacked.