An image forming apparatus has an image bearing member, and a density detecting device for detecting the density of an image for density detection formed on the image bearing member. Image forming conditions are controlled on the basis of an output from the density detecting device. The density detecting device has a regular reflection type density detecting device for detecting the density by regular reflection light from a portion to be detected, and a diffuse reflection type density detecting device for detecting the density by diffuse reflection light from the portion to be detected. The output value from the diffuse reflection type density detecting device is corrected on the basis of the output value from the regular reflection type density detecting device which has detected a reference image, and the output value from the diffuse reflection type density detecting device which has detected the reference image.