The present invention provides a distance-measuring device has an AF area sensor that includes an image pick up element formed on a semiconductor substrate for receiving two images having a parallax therebetween, and a photo reception signal processing circuit formed on the semiconductor substrate for processing signals corresponding to light received by the image pick up element. On the basis of sensor data (outline data) obtained by integration executed in the AF area sensor in an outline detection mode, the distance-measuring device detects a main subject in a photography screen, sets a distance-measuring area including the main subject, and measures a distance to the main subject.