An I-V measurement method is provided for a solar cell having a collecting electrode on the first surface side of a single-crystalline silicon substrate of a first conductivity type and having a transparent electrode on the outermost surface on the second surface side of the single-crystalline silicon substrate of the first conductivity-type. An electric current is supplied to the solar cell in a state in which flexible metal foil and the transparent electrode are brought into detachable contact with each other such that the flexible metal foil follows undulations of the single-crystalline silicon substrate of a first conductivity type, and the first surface is set as a light-receiving surface. It is preferable that at least on a portion that is in contact with the transparent electrode, the metal foil is formed of at least one selected from the group consisting of Sn, Ag, Ni, In, and Cu.