An electronic device comprising: a housing comprising a first face, a second face that faces a direction opposite the first face, and a side face that surrounds a space between the first face and the second face; a front plate disposed on the first face of the housing; a display disposed between at least a partial region of the front plate and the first face, and comprising a first layer and a second layer that are sequentially stacked; a subsidiary material layer disposed between the display and the first face; at least one first seal member (331,332) disposed between an edge portion of the display and the first face; at least one second seal member (333,334) disposed between an edge portion of the front plate and the first face; and a waterproof filler applied to fill a stepped region (311,312,313,314) formed between the first seal member and the second seal member due to a thickness of the display, wherein the first layer and the second layer are disposed such that the first layer is closer to the front plate than the second layer, and when a rear face of the front plate is viewed from above, a part of the first layer protrudes from the second layer in the stepped region, wherein the subsidiary material layer comprises a polymer layer stacked on a second member via a third adhesive member, a functional member stacked on the polymer layer via a fourth adhesive member, and a conductive member stacked on the functional member via a fifth adhesive member, and wherein the polymer layer, the functional member and the conductive member are disposed such that edge regions of the polymer layer, the functional member and the conductive member coincide with each other. a housing comprising a first face, a second face that faces a direction opposite the first face, and a side face that surrounds a space between the first face and the second face; a front plate disposed on the first face of the housing; a display disposed between at least a partial region of the front plate and the first face, and comprising a first layer and a second layer that are sequentially stacked; a subsidiary material layer disposed between the display and the first face; at least one first seal member (331,332) disposed between an edge portion of the display and the first face; at least one second seal member (333,334) disposed between an edge portion of the front plate and the first face; and a waterproof filler applied to fill a stepped region (311,312,313,314) formed between the first seal member and the second seal member due to a thickness of the display, wherein the first layer and the second layer are disposed such that the first layer is closer to the front plate than the second layer, and when a rear face of the front plate is viewed from above, a part of the first layer protrudes from the second layer in the stepped region, wherein the subsidiary material layer comprises a polymer layer stacked on a second member via a third adhesive member, a functional member stacked on the polymer layer via a fourth adhesive member, and a conductive member stacked on the functional member via a fifth adhesive member, and wherein the polymer layer, the functional member and the conductive member are disposed such that edge regions of the polymer layer, the functional member and the conductive member coincide with each other.