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 rotatably mounting the door to the housing and coupling an opening or closing motion of the door with an withdrawal and insertion motion of the tray such that the tray is withdrawn from the cooking compartment when the door is opened and inserted into the cooking compartment when the door is closed; wherein the hinge assembly includes a hinge part and a mounting protrusion; characterized in that the hinge-part is coupled to a rear side of the door upper surface part, wherein a posture of the hinge-part is changeable by interlocking with rotation of the door; and wherein the door is configured to rotate upward about the rear side of the door upper surface part to open the upper surface and the front surface of the housing; and wherein the mounting protrusion is configured for removably mounting the tray thereon and is movable in a horizontal or front-rear direction of the housing for inserting and withdrawing the tray in said direction by interlocking with a change in the posture of the hinge part such that the tray is moved in the front-rear direction. 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 rotatably mounting the door to the housing and coupling an opening or closing motion of the door with an withdrawal and insertion motion of the tray such that the tray is withdrawn from the cooking compartment when the door is opened and inserted into the cooking compartment when the door is closed; wherein the hinge assembly includes a hinge part and a mounting protrusion; characterized in that the hinge-part is coupled to a rear side of the door upper surface part, wherein a posture of the hinge-part is changeable by interlocking with rotation of the door; and wherein the door is configured to rotate upward about the rear side of the door upper surface part to open the upper surface and the front surface of the housing; and wherein the mounting protrusion is configured for removably mounting the tray thereon and is movable in a horizontal or front-rear direction of the housing for inserting and withdrawing the tray in said direction by interlocking with a change in the posture of the hinge part such that the tray is moved in the front-rear direction.