<p>[PROBLEMS] To provide an organic synthesizer that can conduct a pressure reaction and an atmospheric reaction in one organic synthesizer and can realize attachment of reaction vessels to the organic synthesizer and detachment of the reaction vessels from the organic synthesizer without applying any load to gas supply/discharge pipes. [MEANS FOR SOLVING PROBLEMS] An organic synthesizer comprising a reaction vessel support part (160), which can support two or more reaction vessels, and pressure regulation means (164) for regulating the pressure within the reaction vessel supported by the reaction vessel support part (160) by supplying/discharging gas. Two or more pressure regulation means (164) are provided for each reaction vessel supported by the reaction vessel support part (160). At least one pressure regulation means (164A) in the two or more pressure regulation means (164) is constructed so as to be detachable from and attachable to the other pressure regulation means (164B). The pressure regulation means (164) comprises gas supply/discharge pipes (174a to 174d) and openings (194a to 194d) for supporting the gas supply/discharge pipes (174a to 174d). The gas supply/discharge pipes (174a to 174d) are constructed so that a part near the front end can be flexed in a vertical direction and in a lateral direction and are connected to the supported reaction vessels for gas supply and discharge.</p>
