A cooking appliance comprising: a housing having a bottom part, two side parts (120, 130), and a back part, and a cooking compartment formed therein, wherein the housing has an upper surface and a front surface which are open; a door for opening and closing the upper surface and the front surface of the housing, wherein the door is rotatable about a rotation axis parallel to an upper edge of the back part of the housing, and wherein the door includes a door upper surface part for covering the upper surface of the housing and a door front surface part extending from a front portion of the door upper surface part for covering the front surface of the housing; a tray disposed in the cooking compartment; and a hinge assembly, wherein the hinge assembly includes: a mounting protrusion for removably mounting the tray thereon, wherein the mounting protrusion is movable in a horizontal or front-rear direction of the housing for inserting and withdrawing the tray in said direction, and a converting and outputting part configured to convert a rotation of the door to a linear motion of the mounting protrusion in the front-rear direction of the housing, characterized in that the hinge assembly includes: a hinge part hinge-coupled to the rear side of the door upper surface part, and whose posture is changed by interlocking with rotation of the door. a housing having a bottom part, two side parts (120, 130), and a back part, and a cooking compartment formed therein, wherein the housing has an upper surface and a front surface which are open; a door for opening and closing the upper surface and the front surface of the housing, wherein the door is rotatable about a rotation axis parallel to an upper edge of the back part of the housing, and wherein the door includes a door upper surface part for covering the upper surface of the housing and a door front surface part extending from a front portion of the door upper surface part for covering the front surface of the housing; a tray disposed in the cooking compartment; and a hinge assembly, wherein the hinge assembly includes: a mounting protrusion for removably mounting the tray thereon, wherein the mounting protrusion is movable in a horizontal or front-rear direction of the housing for inserting and withdrawing the tray in said direction, and a converting and outputting part configured to convert a rotation of the door to a linear motion of the mounting protrusion in the front-rear direction of the housing, characterized in that the hinge assembly includes: a hinge part hinge-coupled to the rear side of the door upper surface part, and whose posture is changed by interlocking with rotation of the door. a mounting protrusion for removably mounting the tray thereon, wherein the mounting protrusion is movable in a horizontal or front-rear direction of the housing for inserting and withdrawing the tray in said direction, and a converting and outputting part configured to convert a rotation of the door to a linear motion of the mounting protrusion in the front-rear direction of the housing, characterized in that the hinge assembly includes: a hinge part hinge-coupled to the rear side of the door upper surface part, and whose posture is changed by interlocking with rotation of the door.