To provide a reaction vessel capable of ensuring the adhesive strength of a surface acoustic wave element, while suppressing the attenuation of acoustic waves by an adhesive.

The reaction vessel 7, in which a reagent and a specimen are stirred by acoustic waves generated by the surface acoustic wave element 8 attached to the reaction vessel, is used for measuring optical characteristics of a reaction liquid. The surface acoustic wave element 8 in which a surface attached to the reaction vessel 7 is flat, includes an adhesive layer La located in between the surface acoustic wave element and the reaction vessel, for joining them, and a transmission layer Lt in which an attenuation factor per unit length of acoustic waves is smaller than that of the adhesive layer, for transmitting acoustic waves generated by the surface acoustic wave element through the reaction vessel.