A valve body used in a shooting mechanism of an air gun includes a hollow valve body air chamber, a bottom portion of the chamber is detachably closed with a fit lid. A valve body cover is attached to the valve body. The valve body cover includes unit covers that are joined together. The unit covers include a lateral portion forming a part of the valve body cover and a joint. A unit cover bottom portion forms a part or all of the bottom portion of the valve body cover. When the valve body is housed in the unit covers, the unit covers are attached to the circumference of the valve body, and the bottom portion of the valve body cover is closed and may cover the lid.