Detecting a hydraulic pressure condition at a supplied part while reducing the cost of an oil passage forming member provided with an oil passage for conducting oil to the supplied part. In a right cover which is provided with a bent oil passage for conducting oil to a hydraulic type running clutch and which is fitted with the hydraulic pressure sensor, the oil passage is composed of a first hole and a second hole intersecting the first hole so as to constitute a bent passage part. The second hole, which is one of the first hole and the second hole, has an aperture end part with the aperture end part being closed with the hydraulic pressure sensor. The bent passage part is a bent passage part, located at a position nearest to a hydraulic pressure chamber of the running clutch, of the oil passage.