A flow control device is provided with a first body having a first port through which pressure fluid is supplied, and a second body which is installed on the first body. A valve mechanism which controls the circulation state of the pressure fluid that circulates from the first port to a second port is provided inside this first body. Furthermore, a first connecting section of the first body is inserted into and engaged with the inside of a second connecting section formed at the upper end of the second body, resulting in the first body and the second body being integrally connected together.