To provide a function for summing up dispersions of part dimensions so that quality of components judged to be good can be improved and to perform new management.

In an electronic component mounting device 1, an electronic component is attracted and taken out from a component supply unit 3 by an attraction nozzle 33, the electronic component A attracted by the nozzle 33 is image-picked up by a component recognition camera 34, it is recognized by a recognition processor 53, and it is mounted on a printed board P. The device is provided with a RAM 42 storing component library data on the dimensions of the respective electronic components, a CPU 40 judging whether a result obtained by a recognition processing by the recognition processor 53 is within a tolerance at every electronic component type or not, a counter counting the number of the electronic components belonging to a concerned class at every class in which the dimension of the concerned electronic component stored in the RAM 42 as a reference value when it is judged to be within the tolerance by the CPU 40, and the CPU 40 for generating a histogram table based on count values of the counter.