To smoothly carry out the pressed trimming chips of plural kinds of steels by obtaining the sum value of corrected actual volumes of every steel kind, and starting execution of press processing for the trimming chips.

An operating means 7 divides the volume of trimming chips of a steel kind by the corresponding volume efficiency to obtain the corrected trimming chip amount. The above operation is performed for every steel kind to add the corrected trimming chip amounts. If it is judged by the operating means that the corrected trimming chip amount is more than a predetermined value, a control means 9 is started. The control means 9 gives a control signal to a servo valve 13 in such a manner that the servo valve 13 is operated to adjust the inflow and outflow of operating oil and a piston 14 is pushed down to conduct press processing, thereby starting press processing for trimming chips of steel plates of plural steel kinds.