A rotation sensor that has excellent sealing performance for preventing entry of water from the outside, in which a sensor part and a circuit that is provided at the periphery of the sensor part are not damaged by internal heat strain due to internal heat generation and to a variation in temperature in the outside environment, and that can be produced at low cost. The rotation sensor (A) is fixed to a sensor fixation member (7) attached to a bearing for a wheel and detects rotation of a rotation ring of the bearing. A sensor unit (B) is constructed from a magnetic sensor element (1) for detecting a detection target body on the rotation ring, a cable (10) for taking out an output signal of the sensor element (1) to the outside, and a board (11) on which the sensor element (1) and one end of the cable (10) are installed and that has an electricity conduction section (3) for electrically interconnecting an electrode section (2) of the sensor element (1) and a core wire (4) of the cable (10). The sensor unit (B) is fixed to the sensor fixation member (7) by using the board (11). A molding section (8) made by molding thermoplastic elastomer or a rubber material is placed around the sensor unit (B).
