To provide a reaction vessel that does not need the centrifugation upon placing a reaction liquid in a reaction chamber, permits rapidly controlling the temperature of the reaction liquid placed in the reaction chamber, and making the reaction progress even if the amount of the reaction liquid is small.

This reaction vessel has a reaction vessel body having a reaction chamber that has an opening on the top and is capable of containing a reaction liquid, and a lid capable of sealing the opening of the reaction chamber, wherein the lid has a pushing part capable of pushing the reaction liquid placed in the reaction chamber.