An electronic device, comprising: a housing including a first plate oriented in a first direction, a second plate oriented in a second direction opposite the first direction, and a side member oriented in a third direction that is perpendicular to both the first and second directions, the side member surrounding at least a portion of a space defined between the first and second plates; a display panel visible through at least a portion of the first plate; a printed circuit board disposed between the display panel and the second plate; a support member having a first face oriented in the first direction and supporting the display panel, and a second face oriented in the second direction and supporting the printed circuit board, the support member coupled to at least a portion of the side member; a sensor key assembly including a biometric sensor disposed on a key, the key being disposed on at least a portion of the side member having an opening formed therein such that at least a partial face of the biometric sensor is exposed to an exterior of the electronic device, at least the portion of the side member being coupled to the first face of the support member and the sensor key assembly being electrically connected to the printed circuit board using a flexible circuit board; a key assembly structure accommodating the sensor key assembly between the support member and the side member, the key assembly structure including a key bracket accommodated in a portion of the support member so as to support the movement of the biometric sensor in the third direction and enable operation of the sensor key; and at least one waterproof structure mounted on the second face of the support member sealing a second space defined in the housing in which the printed circuit board is located, the second space sealed from a first space defined in the housing in which the sensor key assembly is located. a housing including a first plate oriented in a first direction, a second plate oriented in a second direction opposite the first direction, and a side member oriented in a third direction that is perpendicular to both the first and second directions, the side member surrounding at least a portion of a space defined between the first and second plates; a display panel visible through at least a portion of the first plate; a printed circuit board disposed between the display panel and the second plate; a support member having a first face oriented in the first direction and supporting the display panel, and a second face oriented in the second direction and supporting the printed circuit board, the support member coupled to at least a portion of the side member; a sensor key assembly including a biometric sensor disposed on a key, the key being disposed on at least a portion of the side member having an opening formed therein such that at least a partial face of the biometric sensor is exposed to an exterior of the electronic device, at least the portion of the side member being coupled to the first face of the support member and the sensor key assembly being electrically connected to the printed circuit board using a flexible circuit board; a key assembly structure accommodating the sensor key assembly between the support member and the side member, the key assembly structure including a key bracket accommodated in a portion of the support member so as to support the movement of the biometric sensor in the third direction and enable operation of the sensor key; and at least one waterproof structure mounted on the second face of the support member sealing a second space defined in the housing in which the printed circuit board is located, the second space sealed from a first space defined in the housing in which the sensor key assembly is located.