An image forming device having a detection assembly that detects a detection target. The detection assembly includes an actuator having a shaft rotatable about its axis, an abutment portion extending from the shaft and pivotally movable upon abutment of the detection target, and a detected portion pivotally movable about the axis. A detection board is supported to a stationary base component and includes a detection unit for detecting the detected portion. The shaft has one end portion supported to the base component, and another end portion supported to the detection board. Relative positional relationship between the actuator and the detection unit is maintained by the direct supporting manner of the shaft by the detection board.