The sample plate has a principal plane in which a plurality of wells is arranged. The sample plate has a plurality of through-holes each allowing a sampling needle to pass through in a region of the principal plane where the wells are not provided, and positions of the wells and positions of the through-holes are designed such that when two pieces of the sample plates are arranged up and down with a predetermined positional relationship in a state in which respective principal planes are arranged in parallel each other, the through-holes of the sample plate arranged on an upper side is arranged at positions directly above respective wells of the sample plate arranged on a lower side.