PURPOSE: To attain a high speed and high precision in evaluation by a method wherein a current made to flow through a sample is varied with a magnetic field and a temperature varied gradually, a point whereat a resistance is generated in the sample is recorded and thereby critical characteristics are measured automatically.

CONSTITUTION: A control means 7A controls a current varying means 3A and others, so as to vary a current made to flow through a superconducting sample 1A and the temperature and the magnetic field of a place wherein the sample 1A is set. When a resistance of the sample 1A is detected by a resistance detecting means 4A, the means 7A records values of the strength of the magnetic field, the temperature and the current at that time, and after the current and the temperature are returned to the initial states again, they are increased gradually. When a test is executed with prescribed variation characteristics of the current, the magnetic field and the temperature given at this time, the critical characteristic Jc of the current, the critical characteristic Hc of the magnetic field and the critical characteristic Tc of the temperature are obtained automatically. Besides the test can be executed continuously by giving the prescribed variation characteristics to the current, the magnetic field and the temperature, there is no possibility of the sample 1A being broken down by a Joule heat generated therein, and high-speed and accurate measurement can be executed.