Abstract: A linear recess is provided in a reverse side surface of a synthetic resin base plate 1, and a film 3 covers the linear recess. In this manner, a tunnel-shaped reaction chamber 12 surrounded by the film 3 and the base plate is configured. In addition, a protruding portion 31 is formed in a manner such that the film 3 protrudes into the reaction chamber 12 from the reverse side surface of the base plate 1. Since evaporation of a reagent and the like is suppressed and gaps which are caused by a difference in thermal expansion coefficients between the base plate 1 and the film 3 are formed only in side walls of the reaction chamber 12 and the protruding portion 31 of the film 3, reduction of the reagent and the like is prevented and a reaction product can be sufficiently obtained.