To provide a valve having a small number of components, having an operation lever lock mechanism having a simple structure, and allowing a lock release operation and an operation lever rotation operation with one hand.

This valve 20 for a high-pressure gas vessel is provided with a housing 21, a movable valve element 22, an operation lever 23 and a stopper member 27. The stopper member 27 has a ring-like shape surrounding the operation lever 23, and includes an engagement projection 27a projected downward at its lower end. The stopper member 27 is so held to the operation lever 23 as to move downward by its own weight. The housing 21 has: a support surface 28 for supporting the stopper member 27 from the lower side when the operation lever 23 is at an open position and an intermediate position; and an engagement recessed part 29 for allowing the downward movement of the stopper member 27 to engage with the stopper member 27 when the operation lever 23 is at a close position.