To improve the reliability of a shutoff valve by making a damage of a spring visible.

A tension or pressure spring 23 is arranged outside of the valve casing 1 of this shutoff valve. A pivoting arm 18 is attached to an actuating shaft in the lateral direction. The spring 23 acts on one end of the arm 18 remote from the shaft, and the other end of the spring 23 is held at a support member 20 attached outside of the valve casing 1. An entrained member 22 and the support member 20 are arranged in such a way that in the closed position, an imaginary connection line 24 between the entrained member 22 and the support member 20 extends in the lateral direction to the vertical shaft 17 with a lateral displacement transverse 25 in the direction of closing the valve. The operational state of the spring 23 is visible, and as the valve casing 1 is a lightweight structure, a shutoff mechanism is not necessary for holding a closing member 9 in the open/close position.