PURPOSE: To obtain repeatedly the desired reaction product in a hermetically sealed state by providing a reaction vessel movably in a thermostat through a spring member, and providing a vibrator and a pliable tube for injecting and discharging a sample, a reagent, etc.

CONSTITUTION: A temp. regulator 5 for keeping an almost box-shaped thermostat 1 at a constant temp. is provided to the thermostat 1, and a reaction vessel 10 is provided in the tank 1 movably and in a suspended state through spring members 9. A vibrating and agitating part 11 for vibrating the vessel 10 is provided in the thermostat 1, and pliable tubes 14W17 and 19 for injecting and discharging a sample, a reagent, etc. are simultaneously connected to each end of the vessel 10 to enable the agitation of the sample, etc. injected through the pliable tubes 14W17 in the vessel 10. The desired reaction product can be accordingly obtained repeatedly in a hermetically sealed state without moving the reaction system, and the vibration and agitation of the sample and the reagent can be carried out at a constant temp.