An electronic device, according to various embodiments, may comprise: an outer housing comprising a front plate facing a first direction, a rear plate facing a direction opposite to the front plate, and a side member for surrounding a space between the front plate and the rear plate, wherein the side member protrudes toward the space and includes a protrusion having a first surface facing the first direction; an opaque layer disposed in the space so as to be parallel with the front plate and including a first portion located between the first surface and the front plate, wherein the first portion includes a second surface facing the first surface; an adhesiveness improvement layer formed on the second surface of the opaque layer and having a repetitive pattern; and a waterproof layer disposed between the adhesiveness improvement layer and the first surface and attached to the adhesiveness improvement layer and the first surface. Other various embodiments may be possible.