A scanner unit includes: a tubular elastic part provided with marks outside a prescribed bonding region set on an outer surface thereof and; and a piezoelectric element that is bonded to the bonding region. The piezoelectric element includes: a piezoelectric body having two mutually opposing electrode faces; and marks that are different from each other, respectively provided on the two electrode faces. The mark provided on one electrode face has a shape that matches the mark provided outside the bonding region when the piezoelectric body is bonded to the bonding region so that the other electrode face contacts the outer surface.