a plurality power supply blocks having the same capacity, each of said power supply blocks comprising:

AC-to-DC converting means for converting commercial AC power to DC power; DC-to-high-frequency converting means for converting the resulting DC power to high-frequency power; a transformer for transforming the resulting high-frequency power; high-frequency-to-DC converting means for converting the resulting transformed high-frequency power to DC power; and control means for controlling high-frequency current flowing through said DC-to-high-frequency converting means or current flowing through said high-frequency-to-DC converting means in such a manner as to make said current correspond to a reference signal from reference signal generating means;

said high-frequency-to-DC converting means of said respective power supply blocks having their outputs connected in parallel; said reference signals provided by said reference signal generating means of said respective power supply blocks being kept equal to each other by means of equal-value maintaining means,

wherein each of said reference signal generating means has a reference-potential-side terminal and an output-side terminal; and said equal-value maintaining means comprises a first line connecting said reference-potential-side terminals together and a second line connecting said output-side terminals together.