An electronic device comprising: a housing including a first plate, a second plate facing away from the first plate, and a side member surrounding a space between the first plate and the second plate; a first band detachably mounted to the side member and shaped to wrap around a wrist of a user; a display exposed through the first plate; a processor positioned inside the space and electrically connected to the display; a memory positioned inside the space and electrically connected to the processor; and a mounting structure configured to connect the first band to the side member, wherein the mounting structure includes: a recessed structure formed in the side member, wherein the recessed structure includes a first surface, a second surface facing the first surface, a first hole formed in the first surface, and a second hole formed in the second surface, and facing the first hole, wherein an imaginary line extending from the first hole to the second hole defines a first axis; a rotating member positioned to rotate around the first axis, the rotating member including a through-hole that includes an inner screw surface centered around the first axis; a first rod extending along the first axis through a first portion of the first band, the first rod including a first end inserted into the first hole and a second end held by the rotating member such that the first rod does not move along the first axis while the rotating member rotates; and a second rod extending along the first axis through a second portion of the first band, the second rod including a third end rotatably inserted into the second hole, and an external screw surface engaged with the inner screw surface of the rotating member such that the second rod moves along the first axis while the rotating member rotates. a housing including a first plate, a second plate facing away from the first plate, and a side member surrounding a space between the first plate and the second plate; a first band detachably mounted to the side member and shaped to wrap around a wrist of a user; a display exposed through the first plate; a processor positioned inside the space and electrically connected to the display; a memory positioned inside the space and electrically connected to the processor; and a mounting structure configured to connect the first band to the side member, wherein the mounting structure includes: a recessed structure formed in the side member, wherein the recessed structure includes a first surface, a second surface facing the first surface, a first hole formed in the first surface, and a second hole formed in the second surface, and facing the first hole, wherein an imaginary line extending from the first hole to the second hole defines a first axis; a rotating member positioned to rotate around the first axis, the rotating member including a through-hole that includes an inner screw surface centered around the first axis; a first rod extending along the first axis through a first portion of the first band, the first rod including a first end inserted into the first hole and a second end held by the rotating member such that the first rod does not move along the first axis while the rotating member rotates; and a second rod extending along the first axis through a second portion of the first band, the second rod including a third end rotatably inserted into the second hole, and an external screw surface engaged with the inner screw surface of the rotating member such that the second rod moves along the first axis while the rotating member rotates. a recessed structure formed in the side member, wherein the recessed structure includes a first surface, a second surface facing the first surface, a first hole formed in the first surface, and a second hole formed in the second surface, and facing the first hole, wherein an imaginary line extending from the first hole to the second hole defines a first axis; a rotating member positioned to rotate around the first axis, the rotating member including a through-hole that includes an inner screw surface centered around the first axis; a first rod extending along the first axis through a first portion of the first band, the first rod including a first end inserted into the first hole and a second end held by the rotating member such that the first rod does not move along the first axis while the rotating member rotates; and a second rod extending along the first axis through a second portion of the first band, the second rod including a third end rotatably inserted into the second hole, and an external screw surface engaged with the inner screw surface of the rotating member such that the second rod moves along the first axis while the rotating member rotates.