To provide a temperature characteristic compensation method which can easily compensate the temperature characteristic at the installation field, even in a measuring instrument in which a special pressure converter is externally attached to the main body of the measuring instrument.

In the measuring instrument, in which the pressure converter provided in the measurement environment transmits a fluid pressure generated according to the state of an object to be measured to a pressure sensor provided to the main body of the measuring instrument, and in which the state of the object to be measured in the measurement environment is measured from the fluid pressure applied to the pressure sensor, the measurement environment in which the pressure converter is provided is kept constant, and a temperature cycle is applied to the main body of the measuring instrument. Under the condition in which the temperature cycle is applied, the temperature applied to the pressure sensor and the value measured by the pressure sensor at that time are obtained, respectively, at the temperatures different from each other. Temperature compensation expression for the pressure sensor is obtained from the correlation between the temperature and the measured value, and the value measured by the pressure sensor is compensated.