There is provided an exposing device which includes an elongated optical head in which a plurality of light emitting portions are arranged, and a supporting member to which the optical head is adhered. The optical head and the supporting member are adhered by a first adhesive, and a second adhesive of which a modulus of elasticity after curing is lower than that of the first adhesive. The second adhesive is applied in a second adhesive area which is located at a boundary between the optical head and the supporting member and which is longer, in a longitudinal direction of the optical head, than a first adhesive area which is located at the boundary and to which the first adhesive is applied.