An image forming apparatus configured to form an image on a recording medium conveyed with respect to an image forming unit, said apparatus comprising: a pair of upper frames (210L, 210R) extending substantially in parallel with each other in a vertical direction and an anteroposterior direction perpendicular to the vertical direction so as to support the image forming unit; a pair of lower frames (250L, 250R) provided below the upper frames (210L, 210R) and extending substantially in parallel with the upper frames (210L, 210R) in the anteroposterior direction, each of the lower frames (250L, 250R) having an upper surface and a lower surface opposite the upper surface, the upper surface comprising a plurality of lower supporting portions (255L, 255R) each contacting a lower end of a respective one of the upper frames (210L, 210R) so as to support the respective one of the upper frames (210L, 210R) thereon, and the lower surface comprising a bottom supported portion opposed to a placing surface for supporting the image forming apparatus; and a coupling member (241, 242, 243, 244, 270) that couples the upper frames (210L, 210R) in a bridging manner, wherein a stiffness of each of the upper frames (210L, 210R) in a substantially planar direction along the vertical direction is greater than a stiffness of each of the lower frames (250L, 250R) along the vertical direction between the lower supporting portion (255L, 255R) and the bottom supported portion, wherein the plurality of lower supporting portions (255L, 255R) of each of the lower frames (250L, 250R) comprise a pair of outermost lower supporting portions (255L, 255R) in the anteroposterior direction, wherein a center of gravity of a unit comprising the image forming unit, the upper frames (210L, 210R), the coupling member (241, 242, 243, 244, 270), and a driving unit configured to drive the image forming unit is located closer to one of the upper frames than an intermediate position between the upper frames (210L, 210R), and the center of gravity of the unit being also located inside an outline defined by connecting the outermost lower supporting portions (255L, 255R) of the lower frames (250L, 250R) in plan view, and wherein an anteroposterior distance between the outermost lower supporting portion of the one of the lower frames is greater than an anteroposterior distance between the outermost lower supporting portion of the other of the lower frames. a pair of upper frames (210L, 210R) extending substantially in parallel with each other in a vertical direction and an anteroposterior direction perpendicular to the vertical direction so as to support the image forming unit; a pair of lower frames (250L, 250R) provided below the upper frames (210L, 210R) and extending substantially in parallel with the upper frames (210L, 210R) in the anteroposterior direction, each of the lower frames (250L, 250R) having an upper surface and a lower surface opposite the upper surface, the upper surface comprising a plurality of lower supporting portions (255L, 255R) each contacting a lower end of a respective one of the upper frames (210L, 210R) so as to support the respective one of the upper frames (210L, 210R) thereon, and the lower surface comprising a bottom supported portion opposed to a placing surface for supporting the image forming apparatus; and a coupling member (241, 242, 243, 244, 270) that couples the upper frames (210L, 210R) in a bridging manner, wherein a stiffness of each of the upper frames (210L, 210R) in a substantially planar direction along the vertical direction is greater than a stiffness of each of the lower frames (250L, 250R) along the vertical direction between the lower supporting portion (255L, 255R) and the bottom supported portion, wherein the plurality of lower supporting portions (255L, 255R) of each of the lower frames (250L, 250R) comprise a pair of outermost lower supporting portions (255L, 255R) in the anteroposterior direction, wherein a center of gravity of a unit comprising the image forming unit, the upper frames (210L, 210R), the coupling member (241, 242, 243, 244, 270), and a driving unit configured to drive the image forming unit is located closer to one of the upper frames than an intermediate position between the upper frames (210L, 210R), and the center of gravity of the unit being also located inside an outline defined by connecting the outermost lower supporting portions (255L, 255R) of the lower frames (250L, 250R) in plan view, and wherein an anteroposterior distance between the outermost lower supporting portion of the one of the lower frames is greater than an anteroposterior distance between the outermost lower supporting portion of the other of the lower frames.