An electronic device (101; 200), comprising: a housing including an outer wall at least partially defining an inner space, the outer wall defining a first through hole allowing access into the inner space; an audio module disposed within the inner space; a support structure disposed within the inner space between the audio module and the first through hole, wherein the support structure includes a second through-hole; and a waterproof structure disposed within the inner space between the support structure and the outer wall, wherein the waterproof structure includes a flexible gasket, characterized in that the flexible gasket includes: an outer rim fixed between the support structure and a portion of the outer wall as to circumferentially surround the first through hole; a recess portion movably interposed between the first through hole and the second through hole, wherein the recess portion is oriented towards the second through hole such that when no external pressure is applied, the recess portion may be spaced apart from the peripheral portion of the second through hole by a predetermined distance, and when an external pressure is applied, the recess portion may be elastically moved and positioned to be in contact with the peripheral portion of the second through hole; and a connection portion formed between the rim and the recess portion, wherein the connection portion includes at least one opening around the recess portion, such that the at least one opening and the second through-hole form at least part of a path through which sound can propagate between the audio module and the first through hole in the absence of pressure applied against the recess portion by an external liquid. a housing including an outer wall at least partially defining an inner space, the outer wall defining a first through hole allowing access into the inner space; an audio module disposed within the inner space; a support structure disposed within the inner space between the audio module and the first through hole, wherein the support structure includes a second through-hole; and a waterproof structure disposed within the inner space between the support structure and the outer wall, wherein the waterproof structure includes a flexible gasket, characterized in that the flexible gasket includes: an outer rim fixed between the support structure and a portion of the outer wall as to circumferentially surround the first through hole; a recess portion movably interposed between the first through hole and the second through hole, wherein the recess portion is oriented towards the second through hole such that when no external pressure is applied, the recess portion may be spaced apart from the peripheral portion of the second through hole by a predetermined distance, and when an external pressure is applied, the recess portion may be elastically moved and positioned to be in contact with the peripheral portion of the second through hole; and a connection portion formed between the rim and the recess portion, wherein the connection portion includes at least one opening around the recess portion, such that the at least one opening and the second through-hole form at least part of a path through which sound can propagate between the audio module and the first through hole in the absence of pressure applied against the recess portion by an external liquid. an outer rim fixed between the support structure and a portion of the outer wall as to circumferentially surround the first through hole; a recess portion movably interposed between the first through hole and the second through hole, wherein the recess portion is oriented towards the second through hole such that when no external pressure is applied, the recess portion may be spaced apart from the peripheral portion of the second through hole by a predetermined distance, and when an external pressure is applied, the recess portion may be elastically moved and positioned to be in contact with the peripheral portion of the second through hole; and a connection portion formed between the rim and the recess portion, wherein the connection portion includes at least one opening around the recess portion, such that the at least one opening and the second through-hole form at least part of a path through which sound can propagate between the audio module and the first through hole in the absence of pressure applied against the recess portion by an external liquid.