To provide a signal value expressing method widening a dynamic range and improving accuracy with a low power supply voltage through expressing one signal by combining plural digital signal value expressions and one analog signal value expression, and making a value to be expressed by the analog signal value expression equal to the minimum value of a digital signal value expressing method.

This method has a signal line 1 composed of M pieces of signal lines expressed by a digital signal value expressing system and a signal line 2 composed of one signal line expressed by an analog signal value expressing method, and the exchange of a signal with an information processing means 4 is performed, while using the signal lines 1 and 2. The discrete value internal of a signal expressed by M pieces of digital signal value expressing methods is made equal with a value, which can be expressed by one analog signal value expressing method. The signal value is expressed, while combining a signal to be changed discretely, while having the wide dynamic range expressed by M pieces of digital signal value expressing methods and a high-accuracy continuously variable signal.