The object of the present invention is to provide an optical scanning apparatus which is not limited in the disposition of a scanning device, can reduce the adherence of dust to each member of the scanning device, and is enhanced in the reliability of the scanning device, and an image displaying apparatus having the same. The optical scanning apparatus includes a housing for containing and holding therein a scanning device provided with a movable mirror, an elastic supporting portion for supporting the movable mirror swingably about a swinging center, and a supporting base for supporting the elastic supporting portion, an optical member OE constituting a first optical system for directing a beam to the scanning device in the housing, and an optical member OX constituting a second optical system for emerging the beam passed through the scanning device. At least a part of the optical member OE and at least a part of the optical member OX constitute a part of the housing, and are provided so that a space in which the scanning device is contained in the housing configures a sealed space.