An inspection method for inspecting a counting function of an imaging system that captures an image of a phase object includes: capturing an image of a reference standard plate that includes a base region and a plurality of counting target regions having a phase amount in a thickness direction different from a phase amount of the base region, under a condition where the number of counting target regions positioned within a field of view of the imaging system is specified among the plurality of counting target regions; counting the counting target regions included in the captured image of the reference standard plate; and outputting at least a counted result of the counting target regions.