The present invention relates to an immunoassay device and an immunoassay method. According to an aspect of the present invention, an immunoassay device includes a measurement unit provided with a detection unit disposed at one side of a stage accommodating cartridges having a plurality of wells to move in a direction, in which the plurality of cartridges are arranged, and capable of measuring a state within the well disposed at the outermost side, and including a shielding plate that moves to cover an opened upper portion of the well disposed at the outermost side to block introduction of light into the well.