A sensor body has a body recess portion, in which a sensor element is housed and the body recess portion opens at a body opening portion. A sensor cover has a cover window which communicates between the intake passage and the body opening portion, and the sensor cover covers the sensor body. A sensor filter is provided with a sensor peripheral portion which extends along a virtual surface. In a projection view with respect to the virtual plane the body opening portion and the cover window are positioned within a filtering area which is defined as an inner side of a contour of the filter peripheral portion, such that the filter peripheral portion contacts the sensor body and the sensor cover.
