A component mounting machine including a mounting head configured to pick up and mount a component; a component camera to image the component from below the mounting head; a board camera to image the circuit board from above; an imaging position memory to memorize imaging position coordinates during imaging, based on images acquired by the component camera; a relative position memory to memorize relative position coordinates that are a relative position of the mounting head with respect to the board camera; and a correction necessity determining section to perform imaging of the mounting head by the component camera when the moving device has arrived at the imaging position coordinates, and determine whether it is necessary to correct the relative position coordinates memorized in the relative position memory, based on a position of the mounting head understood from the images acquired from the imaging.