The present invention provides a modesty panel capable of being stably attached to a fixing surface of a building side regardless of the unevenness of the fixing surface, and an external wall construction structure in which the modesty panel is attached. In the external wall construction structure, a base member 10 provided with an upper attaching portion 12 and a lower attaching portion 13 is fixed to the building external wall surface 2. The base member 10 has first and second engaging stepped portions 16 and 17. To this base member 10, a modesty panel main body 30, provided with first and second engaging ridges 32 and 33, is outwardly engaged. In a superimposed region S formed by the engagement, a fixing screw 4 is screwed to integrally and firmly fix the modesty panel main body 30 and the base member 10.