PURPOSE: To improve operability at the time of switching sorts by receiving the sort of an object to be processed after starting collection.

CONSTITUTION: In the step S21, inputted sort number data are written in a temporary storage area. During the collection of data, the sort number data stored in the sort number area are read out and whether data collection is executed prior to the input of the sort number or not is judged (S23) by judging whether the read data are null data or not. When the sort number has been inputted, whether the sort number data read out from the sort number area coincide with the inputted sort number data stored in the sort temporary storage area or not is judged (S24), and when both the data mutually different, a new storage area is prepared to input a new sort (S25). Then new sort number data written in the sort temporary storage area are written in the newly secured area (S26).