An image forming apparatus is provided which includes a housing, a series of photoconductors on which an electrostatic latent image is formed, and developing devices, which each include a developing agent carrier for holding a developing agent. Also, the apparatus may include a holder, which is removable from the housing, for supporting the photoconductors and the developing devices, and an image reader provided at a top portion of the housing, which is configured to read an image on a document.