A film covered battery (1) has a flat shape with an outer cover member (5) formed of a laminate film to accommodate therein a battery element (4) together with an electrolytic solution. For reliable inspection of an insulation failure between a metal layer (52) of the laminate film and a negative electrode plate (42) of the battery element (4), an inspection test is performed on the film covered battery by a first inspection device (73) under a condition where pressure is applied to a center region of the outer cover member (5) by a first press bar (72); and an inspection test is performed on the film covered battery by a second inspection device (83) under a condition where pressure is applied to the remaining side regions of the outer cover member (5) by a second press bar (82).