To increase the total number of sensor pairs satisfying specifications of measurement accuracy determined to different output, and to decrease the number of sensor single bodies which are waisted by finding no pair.

For example, if a physical quantity sensor is made to be a pressure sensor, all pressure sensors which can be combined and the number of those are obtained from a maximum value and a minimum value of an accuracy index of output characteristics of each pressure sensor. A pressure sensor having the smallest number of sensors which can be combined is selected as a first pressure sensor. Then, a pressure sensor having the smallest number of sensors which can be combined is selected from the pressure sensors which can be combined with the selected pressure sensor as a second sensor. Among the rest pressure sensors, the selection of the first pressure sensor and the second pressure sensor is repeated in the same way.