A connector 10 is made of a socket 20, a plug 30, and a removal prevention mechanism 40. The removal prevention mechanism 40 includes a slider tube 41 slidably mounted on a first body 21, a stop ring 42 mounted on the outer circumferential surface of the first body 21, a helical spring 43 resiliently disposed between the slider tube 41 and a socket member 22, a ball 44 movably mounted in a through hole 41C defined in the slider tube 41, a cavity 45 defined in the outer circumferential surface of the first body 21 for the ball 44 to drop therein, and an engaging surface 46 defined in the inner circumferential surface of the plug member 32, for engaging the ball 44.