An air cleaner unit includes a casing and a filter element disposed in the casing for filtering air to be introduced into an internal combustion engine of a vehicle. The casing includes a first case member and a second case member that are coupled to each other such that the filter element is housed in an element housing portion of the casing. The first case member has a hinge receiving portion, and the second case member has a hinge inserting portion. The hinge receiving portion and the hinge inserting portion are disposed under the element housing portion. The hinge receiving portion includes an engagement opening in which the hinge inserting portion is received such that the hinge receiving portion and the hinge inserting portion are connected in a hinge manner. The hinge receiving portion further includes a hinge receiving surface that extends from a vicinity of the engagement opening.