Provided are a radiation emitting device forming a radiography apparatus, a method for controlling the radiation emitting device, and a program which can reduce power consumption. A radiation emitting device includes a radiation source, a collimator that sets a radiation field region, imaging unit for capturing an image of an imaging target, a display unit that displays the image captured by the imaging unit, an exposure switch, and a control unit that issues a collimator driving command to direct the collimator to set the radiation field region determined from the captured image to the collimator in a case in which the exposure switch is operated.