An image forming apparatus, comprising: a chassis having an opening; an image forming unit, which is configured to form a toner image on a recording medium; a door, which is disposed at the opening of the chassis and configured to be movable in a range between an open position and a closed position with respect to the chassis; a fixing unit, which is configured to nip the recording sheet with the toner image formed thereon by nipping pressure and fix the toner image on the recording sheet; a frame, which is arranged inside the chassis and extend along a direction of a line connecting the door and the fixing unit; a linear motion member, which extends along the line connecting the door and the fixing unit; characterized by a guiding member (51, 55), which is formed in the frame and configured to guide the linear motion member to move linearly in a motion path along the line connecting the door and the fixing unit; a coupler assembly, which is configured to couple the door with the linear motion member and move the linear motion member in the motion path according to opening and closing motions of the door; and a manipulation member (184, 185, 186), which is movable according to the linear motion of the linear motion member and is configured to place the fixing unit in one of a nipping condition, in which the recording sheet is nipped by the nipping pressure in the fixing unit, and a nip-relaxed condition, in which nipping pressure is relaxed in the fixing unit; wherein the linear motion member includes a contact portion, with which the manipulation member (184, 185, 186) comes in contact along an intersecting direction to intersect the motion path of the linear motion member when the linear motion member moves the manipulation member (184, 185, 186), on a surface thereof; wherein the guiding member (51, 55) includes a slider plane to slidably support the linear motion member and to bear reaction force from the manipulation member (184, 185, 186); and wherein the linear motion member is slidably supported by the slider plane of the guiding member (51, 55) at a surface which is on an opposite side from the surface having the contact portion. a chassis having an opening; an image forming unit, which is configured to form a toner image on a recording medium; a door, which is disposed at the opening of the chassis and configured to be movable in a range between an open position and a closed position with respect to the chassis; a fixing unit, which is configured to nip the recording sheet with the toner image formed thereon by nipping pressure and fix the toner image on the recording sheet; a frame, which is arranged inside the chassis and extend along a direction of a line connecting the door and the fixing unit; a linear motion member, which extends along the line connecting the door and the fixing unit; characterized by a guiding member (51, 55), which is formed in the frame and configured to guide the linear motion member to move linearly in a motion path along the line connecting the door and the fixing unit; a coupler assembly, which is configured to couple the door with the linear motion member and move the linear motion member in the motion path according to opening and closing motions of the door; and a manipulation member (184, 185, 186), which is movable according to the linear motion of the linear motion member and is configured to place the fixing unit in one of a nipping condition, in which the recording sheet is nipped by the nipping pressure in the fixing unit, and a nip-relaxed condition, in which nipping pressure is relaxed in the fixing unit; wherein the linear motion member includes a contact portion, with which the manipulation member (184, 185, 186) comes in contact along an intersecting direction to intersect the motion path of the linear motion member when the linear motion member moves the manipulation member (184, 185, 186), on a surface thereof; wherein the guiding member (51, 55) includes a slider plane to slidably support the linear motion member and to bear reaction force from the manipulation member (184, 185, 186); and wherein the linear motion member is slidably supported by the slider plane of the guiding member (51, 55) at a surface which is on an opposite side from the surface having the contact portion.