Abstract: A connection mechanism 242 of the present invention is configured such that, in a state where an inclined end surface 536 of a male connection portion 500 is brought into contact with a protruding portion 618 of a female connection portion 600, by moving the male connection portion 500 toward the female connection portion 600, the male connection portion 500 rotates and the protruding portion 618 is inserted into a guide portion 534 and a connector 532 is connected to an adapter 610. The lock mechanism 243 is configured such that the protrusion 704 of the male lock portion 700 comes in contact with a wall 858 of a circumferential recess 842 disposed in a proximal cylindrical member 806 of the female lock portion 800, and in this state, the proximal cylindrical member 806 is further moved toward a proximal fixing member 804 against an urging force of a spring 854, and then the male lock portion 700 is rotated to move to a space 856 of the circumferential recess 842.