Patent ID: 7847540

Claim:
A contactless rotation angle sensor comprising: a detection shank which is provided with a magnetism generation body at its outer periphery, coupled to a rotating body to be detected and integrally rotates therewith; and a housing which is formed of an insulating housing main body concentrically arranged around the detection shank and a cover for covering the upper portion of the housing main body and serves as a fixing side with a space left between the housing and detection shank; the contactless rotation angle sensor storing a circuit board at a circuit-board arrangement portion formed at the upper portion of the housing main body and covered with the cover and holding in the housing main body a detection body detecting a magnetism generation body in a contactless manner and outputting a detected signal to the circuit board, wherein a waterproof surface on the main body side positioned at the inner periphery of the circuit-board arrangement portion and rising toward the cover is circumferentially provided at the inner periphery of the housing main body, the waterproof surface on the main body side opposes the outer periphery of the detection shank through a space across from the upper to the lower portion of the housing main body, a waterproof surface on the cover side disposed opposite to the upper inner periphery of the waterproof surface on the main body side is circumferentially provided at the lower surface of the cover and a ditch passing between the upper and the lower portion of the housing is formed of the space between the detection shank and the housing and between the detection shank and the waterproof surface on the main body side.