A wearable electronic device comprising: a housing; and a strap detachably fastened to at least a part of the housing, wherein the strap comprises: a plurality of unit links (510,520,530); a button exposed from at least one of the plurality of unit links so as to be operable; a tension rib, secured to an end portion of the button at a rib-fixing protrusion of the button, in an internal space of the unit link and having opposite ends, the positions of the opposite ends being changed by pressing of the button; and a hinge pin (514,515) secured to each of the opposite ends of the tension rib, and disposed to at least partially protrude from left and right sides of each of the unit links, wherein the plurality of unit links (510,520,530) are fastened to or separated from each other, such that the hinge pins (514,515) of a unit link, are inserted into, moving by means of the releasing of the button, or extracted from, moving by means of the pressing of the button, pin-receiving recesses formed in an adjacent unit link, the wearable electronic device is characterized in that, the tension rib is supported by a pair of rib-stopping pieces protruding beyond the bottom of a button-receiving space of the unit link and arranged such that the tension rib is deformed by the pressing of the rib-fixing protrusion and the support of the rib stopping pieces. a housing; and a strap detachably fastened to at least a part of the housing, wherein the strap comprises: a plurality of unit links (510,520,530); a button exposed from at least one of the plurality of unit links so as to be operable; a tension rib, secured to an end portion of the button at a rib-fixing protrusion of the button, in an internal space of the unit link and having opposite ends, the positions of the opposite ends being changed by pressing of the button; and a hinge pin (514,515) secured to each of the opposite ends of the tension rib, and disposed to at least partially protrude from left and right sides of each of the unit links, wherein the plurality of unit links (510,520,530) are fastened to or separated from each other, such that the hinge pins (514,515) of a unit link, are inserted into, moving by means of the releasing of the button, or extracted from, moving by means of the pressing of the button, pin-receiving recesses formed in an adjacent unit link, the wearable electronic device is characterized in that, the tension rib is supported by a pair of rib-stopping pieces protruding beyond the bottom of a button-receiving space of the unit link and arranged such that the tension rib is deformed by the pressing of the rib-fixing protrusion and the support of the rib stopping pieces. a plurality of unit links (510,520,530); a button exposed from at least one of the plurality of unit links so as to be operable; a tension rib, secured to an end portion of the button at a rib-fixing protrusion of the button, in an internal space of the unit link and having opposite ends, the positions of the opposite ends being changed by pressing of the button; and a hinge pin (514,515) secured to each of the opposite ends of the tension rib, and disposed to at least partially protrude from left and right sides of each of the unit links, wherein the plurality of unit links (510,520,530) are fastened to or separated from each other, such that the hinge pins (514,515) of a unit link, are inserted into, moving by means of the releasing of the button, or extracted from, moving by means of the pressing of the button, pin-receiving recesses formed in an adjacent unit link, the wearable electronic device is characterized in that, the tension rib is supported by a pair of rib-stopping pieces protruding beyond the bottom of a button-receiving space of the unit link and arranged such that the tension rib is deformed by the pressing of the rib-fixing protrusion and the support of the rib stopping pieces.