To execute various tests of equipment appropriately, quickly and easily.

An analog timer of a DC voltge generator 10 acts upon the lapse of specified time after closing a power switch and gives a cutoff command of cutting off a base current of a semiconductor switch 19 to stop its action, and impression of voltage of the DC voltage generator to tested equipment from terminals A, B serving as first terminals is controlled to the fixed time by the action stop of the semiconductor switch 19. An insulation resistance measuring switch S2 is switched from the respective terminal a, c side to b, d side, so that insulation resistance is measured by an insulation resistance measuring apparatus 20 without being influenced by an internal circuit of the DC voltage generator.