To provide isolation system of an endoscope apparatus capable of steadily ensuring electrical isolation of the first circuit and patient's circuit concurrently implementing size reduction of the apparatus itself as well as product cost reduction.

In the isolation system of an endoscope apparatus equipped with an inner circuit to be electrically connected to the endoscope as well as a transmitter 20 to give the inner circuit a second voltage gained by transforming the first voltage input by an outer power source, at least one of first coil 21 or second coil 22 of the transmitter 20 is wrapped up by metal members 25, 26 which are to be protected and grounded. Thickness of the metal members 25, 26 is specified to be more than 0.13mm.