An automatic focusing adjusting device for use in a camera is disclosed in which an operation processing on the phase difference detection to be executed when the focusing of an image pickup optical system is detected can be performed by means of an analog signal processing. In the automatic focusing adjusting device, when the distance measurement ranges in a light receiving part of sensor means are specified by operation means, then control means controls charge input preventive means in such a manner that only the signal electric charges that are stored in photoelectric conversion elements forming the light receiving part but belonging to the other distance measurement ranges that the ranges specified by the operation means are prevented from flowing into a readout part in the sensor means, whereby the distance measurement ranges in the light receiving part of the sensor means can be changed. Also, in the adjusting device, based on the output signal of the operation means or on the distance measurement information obtained from the sensor means, the distance measurement ranges in the light receiving part of the sensor means can be changed and the changed versions of the distance measurement ranges can be visibly displayed on display means.