To easily confirm a changed input function in a safe state.

A CPU 14 monitors the presence or the absence of the operation of a stop key (step ST1), and when the operation of the stop key is performed (step ST1: Yes), performs stop processing (step ST3) when an AC motor 3 in operation (step ST2: Yes), and is directly shifted to a function confirmation mode (step ST4 to step ST6) when the AC motor 3 is in a stop (step ST2: No). In the function confirmation mode, when an "input name" is inputted from an input device 16 (step ST5: Yes) during the long push of the stop key (step ST4: Yes), a corresponding "function number" in a input device list table is referred to, and the matched "function number" is extracted by searching the input function list table (step ST6), thereby indicating the "function number" to an indication part (step ST7).