PURPOSE: To reduce the processing time in data transfer and improve the reliability of data transfer by making common use of an electric desk calculator part and the basic clock generating circuit of an interface part.

CONSTITUTION: A measuring part A converts a signal VIN to be measured from analog to digital and displays the same in a display circuit 3, and outputs the results of the measurement to an interface part C. An electric desk calculator part B takes therein the transfer data outputted from a keyboard 6 and the part C by a numerical operating circuit 4, and displays the results of operation in a display circuit 5. When the part C receives a transfer start signal from the keyboard 6, it takes therein the results of measurement from the part A, and transfers the measurement value at the prescribed timing of the part B. A basic clock generating circuit 10 is commonly used for the part B and the part C. Thereby, entire power consumption is reduced, and the effective time in data transfer is reduced.