An image forming apparatus includes a casing having an opening that is open upward, a cover configured to open and close the opening, a process cartridge, and a guide. The guide is configured to guide the process cartridge in the casing while changing a position of the process cartridge. The process cartridge includes a photosensitive member, a first guided portion and a second guided portion. The guide includes a first guide configured to guide the first guided portion and a second guide configured to guide the second guided portion. The second guide has an upper portion disposed on an upstream side in an attaching direction of the process cartridge, and a lower portion extending smoothly from a lower end of the upper portion to a stop position in which the second guided portion is disposed. The lower portion is curved away from the first guide.