1. An electronic device comprising:a first cover forming a first surface of the electronic device;
a second cover forming a second surface of the electronic device;
a side member surrounding an inner space between the first cover and the second cover; and
a display disposed in the inner space and viewed through at least a portion of the first cover,
wherein the side member includes a metal portion forming a third surface between the first surface and the second surface of the electronic device and a polymer portion bonded to the metal portion,
wherein the polymer portion includes a first portion facing an edge of the first cover and/or an edge of the second cover, and
wherein, when viewed in a direction substantially perpendicular to the third surface, the first portion of the polymer portion is covered by the metal portion such that the first portion is invisible from an outside of the electronic device.