A projection type image display apparatus includes an image display element, a projection unit including a first lens group and a second lens group formed with a plural number of lenses, a reflection mirror configured to reflect light emitted from the second lens group thereon after the light passes through the first lens group so as to project the light on a screen obliquely, and a mechanism configured to enable movement of at least one lens of the second lens group in a direction of an optical axis. The first lens group is fixed with respect to a bottom portion of the mechanism and is configured to compensate for an aberration of an optical system thereof. The second lens group is configured to enable movement of at least one lens of the second lens group with respect to the first lens group and the bottom portion of the mechanism.