PURPOSE: To reduce the leak current measuring time by measuring leak current with input/output terminals of a semiconductor element divided into two groups by odd and even sequence utilizing the fact that the leak current flows between adjacent input/outut terminals.

CONSTITUTION: Input/output terminals of a semiconductor 19 excluding power source terminals 14 and 18 are divided into two groups by odd and even sequence and the input/output terminals 11, 13 and 16 in the first group are connected together with a wire 20 while the input/output terminals 12, 15 and 17 in the second group are connected together with a wire 21. When a reference voltage is applied to terminals 14 and 18 while diffrent leak measuring voltages are applied into the wires 20 and 21 respectively, leak current flows between adjacent input/output terminals. If this fact is utilized, the leak current flowing through the element 19 equivalent to the total of leak currents flowing between the input/output terminals in the first and second groups and the power source terminals can be measured once without measuring leak current for each of the input/output terminals by switching the connection. Thus, the leak current measing time can be reduced.