An image forming apparatus comprising: a main body; a plurality of polygon motors (30Y, 30M, 30C, 30K); a plurality of exposing portions (3Y, 3M, 3C, 3K) arranged along a vertical direction of the main body, each exposing portion including a respective polygon motor, each exposing portion for forming a latent image on an image-supporting member based on image data by driving of the polygon motor; a plurality of cases (32Y, 32M, 32C, 32K) arranged along the vertical direction, each case containing a respective exposing portion (3Y, 3M, 3C, 3K); a plurality of developing portions (4Y, 4M, 4C, 4K) arranged along the vertical direction, each developing portion for developing the latent image formed by an exposing portion using toner; a partition member that partitions a region between a space in which the cases containing the exposing portions are positioned and a space in which the developing portions are positioned, the partition member being provided between the space in which the cases containing the exposing portions are positioned and the space in which the developing portions are positioned; and a cooling portion for cooling the exposing portions and the developing portions, wherein the cooling portion includes an intake fan, wherein a projection portion (3Ym, 3Mm, 3Cm, 3Km) of each exposing portion including each respective polygon motor projects from the partition member toward the space in which the developing portions are positioned; wherein each of the developing portions and each of the projection portions are alternately arranged along the vertical direction so as to be overlapped with at least a part of each other on the vertical direction, and wherein each of the projection portions and each of the developing portions are positioned so that they are away from each other with a clearance, the clearance being a passage (P1, P2, P3, P4, P5, P6, P7) for a flow of air taken into the apparatus by the intake fan. a main body; a plurality of polygon motors (30Y, 30M, 30C, 30K); a plurality of exposing portions (3Y, 3M, 3C, 3K) arranged along a vertical direction of the main body, each exposing portion including a respective polygon motor, each exposing portion for forming a latent image on an image-supporting member based on image data by driving of the polygon motor; a plurality of cases (32Y, 32M, 32C, 32K) arranged along the vertical direction, each case containing a respective exposing portion (3Y, 3M, 3C, 3K); a plurality of developing portions (4Y, 4M, 4C, 4K) arranged along the vertical direction, each developing portion for developing the latent image formed by an exposing portion using toner; a partition member that partitions a region between a space in which the cases containing the exposing portions are positioned and a space in which the developing portions are positioned, the partition member being provided between the space in which the cases containing the exposing portions are positioned and the space in which the developing portions are positioned; and a cooling portion for cooling the exposing portions and the developing portions, wherein the cooling portion includes an intake fan, wherein a projection portion (3Ym, 3Mm, 3Cm, 3Km) of each exposing portion including each respective polygon motor projects from the partition member toward the space in which the developing portions are positioned; wherein each of the developing portions and each of the projection portions are alternately arranged along the vertical direction so as to be overlapped with at least a part of each other on the vertical direction, and wherein each of the projection portions and each of the developing portions are positioned so that they are away from each other with a clearance, the clearance being a passage (P1, P2, P3, P4, P5, P6, P7) for a flow of air taken into the apparatus by the intake fan.