Abstract: Provided is an object detecting device that does not require an operator to perform a complicated operation onsite and that allows the number of components to be reduced while a detection range can be set. Provided are: at least two sensor units configured to receive detection rays from different detection areas, the different detection areas being arranged in an up-down direction and having center lines extending in different diagonally downward directions; and an object detection determination section configured to detect an object in a detection range based on one or more of at least two detection signals corresponding to amounts of detection rays received by the at least two sensor units, respectively, the detection range being determined by setting a reference for the at least two detection signals.