The invention provides a socket assembly method, an assembly device, and a valve for endoscope. Connecting ducts (11a)-(11d) are arranged on through holes (13a)-(13d) with steps and a valve socket(10) to maintain the valve socket on a platform (23) and engage with the connecting ducts (11a)-(11d) which are formed by filling solder (17) in a rod (28a) for centering adjustment passing through insertion holes (27a)-(27d) disposed on arm support (25), (26). The valve socket abuts to a step face (16) relatively to the through hole (13) during the process of centering adjustment. An annular gap (G) is formed between the outer circumference surface of the connecting duct (11) and the inner circumference surface of a major diameter part (14). The solder (17) is melted via high frequency induction heating equipment (40) to make the solder (17) porous into the gap (G). Thereby, the connecting ducts can be connected onto the through hole with step of the socket body firmly without special process.
