A lever device may include a movable component including a pair of support arm portions. The lever device may also include an operable knob provided with a base end portion inserted between the pair of support arm portions, the base end portion being supported by the pair of support arm portions to be rotatable around a first axis line. The lever device may further include a fixed component configured to assemble a polar board and a cover in a direction of a second axis line perpendicular to the first axis line, the movable component being supported to be rotatable around the second axis line in the fixed component. Arc-shaped guide grooves to surround the second axis line by a predetermined interval as viewed in the direction of the second axis line may be provided respectively on opposing faces of each other of the polar board and the cover. Projections engaging to the guide groove in a polar board side and the guide groove in a cover side may be provided in the support arm portion.