A refrigerator comprising: a main body having a front side thereof open; and a door configured to open and close the open front side of the main body, wherein the door includes: a door body including: an upper door cap including a coupling groove at a front portion of the upper door cap, a cap hole, and a through hole on an upper side of the upper door cap; a cover forming a front surface of the door body, and chassis (121, 126) forming opposite side surfaces of the door body, a door panel detachably mountable on the door body, and the door panel including: a panel body; and a fixer on a rear surface of the panel body, and including a protrusion having a fixing hole, a fastening member, and a cap cover mountable on the upper door cap, wherein the door body, the door panel, the fastening member and the cap cover are configured so that, when the door panel is mounted on the door body, the rear surface of the panel body faces the cover, the protrusion protrudes into the coupling groove and is accommodated in the upper door cap so that the fixing hole and the cap hole are vertically aligned with each other, the fastening member is accommodated in the upper door cap through the through hole and extends into the fixing hole and the cap hole, and the cap cover covers the through hole. a main body having a front side thereof open; and a door configured to open and close the open front side of the main body, wherein the door includes: a door body including: an upper door cap including a coupling groove at a front portion of the upper door cap, a cap hole, and a through hole on an upper side of the upper door cap; a cover forming a front surface of the door body, and chassis (121, 126) forming opposite side surfaces of the door body, a door panel detachably mountable on the door body, and the door panel including: a panel body; and a fixer on a rear surface of the panel body, and including a protrusion having a fixing hole, a fastening member, and a cap cover mountable on the upper door cap, wherein the door body, the door panel, the fastening member and the cap cover are configured so that, when the door panel is mounted on the door body, the rear surface of the panel body faces the cover, the protrusion protrudes into the coupling groove and is accommodated in the upper door cap so that the fixing hole and the cap hole are vertically aligned with each other, the fastening member is accommodated in the upper door cap through the through hole and extends into the fixing hole and the cap hole, and a door body including: an upper door cap including a coupling groove at a front portion of the upper door cap, a cap hole, and a through hole on an upper side of the upper door cap; a cover forming a front surface of the door body, and chassis (121, 126) forming opposite side surfaces of the door body, an upper door cap including a coupling groove at a front portion of the upper door cap, a cap hole, and a through hole on an upper side of the upper door cap; a cover forming a front surface of the door body, and chassis (121, 126) forming opposite side surfaces of the door body, a door panel detachably mountable on the door body, and the door panel including: a panel body; and a fixer on a rear surface of the panel body, and including a protrusion having a fixing hole, a panel body; and a fixer on a rear surface of the panel body, a fastening member, and a cap cover mountable on the upper door cap, wherein the door body, the door panel, the fastening member and the cap cover are configured so that, when the door panel is mounted on the door body, the rear surface of the panel body faces the cover, the protrusion protrudes into the coupling groove and is accommodated in the upper door cap so that the fixing hole and the cap hole are vertically aligned with each other, the fastening member is accommodated in the upper door cap through the through hole and extends into the fixing hole and the cap hole, and the rear surface of the panel body faces the cover, the protrusion protrudes into the coupling groove and is accommodated in the upper door cap so that the fixing hole and the cap hole are vertically aligned with each other, the fastening member is accommodated in the upper door cap through the through hole and extends into the fixing hole and the cap hole, and