A pressure switch comprising an external force transmission mechanism separating a cover and a housing, a first pressure chamber sectioned by the cover and the external force transmission mechanism, and a second pressure chamber sectioned by the housing and the external force transmission mechanism. The second pressure chamber is provided with a movable piece having first and second movable portions located oppositely, and one or more fixed contacts. The first and second movable portions are coupled through a leaf spring. The second movable portion is provided with a contact functioning as a movable contact. When the external force transmission mechanism applies an external force to the first movable portion, the first movable portion is displaced, the second movable portion is reversed at the action point of the first movable portion, and thus the movable contact comes into contact with the fixed contact.