A device and a method for detecting the position of a developing unit mounted in an image forming apparatus are provided. The device includes an image forming controller outputting a clock signal for accessing first to Nth (N is a positive integer greater than 1) developing units, a switching unit performing a switching operation for connecting the image forming controller to a Kth (K is a positive integer greater than 1 and equal to or smaller than N) mounting slot in order to transmit the clock signal to the Kth mounting slot among first to Nth mounting slots in which the first to Nth developing units are mounted, respectively, first to Nth clock signal lines connecting the switching unit to the first to Nth mounting slots, and a data line commonly connecting the image forming controller to the first to Nth mounting slots, wherein the switching unit performs the switching operation in accordance with a switching signal for connecting the image forming controller to the Kth mounting slot and the image forming controller determines whether the Kth developing unit is mounted on the Kth mounting slot in response to reception of an access signal from the Kth mounting slot.