An object of the present invention is to suppress conduction between an anode and a cathode caused by condensed water in an oil removal apparatus in which oil particles are collected in a filter disposed between the anode and the cathode. An insulating layer is sandwiched either between the filter and at least one of the anode and the cathode of the bipolar electrode, or within the filter so as to extend in a flow direction of blow-by gas, and has an insulating property so as to prevent condensed water generated when moisture in the blow-by gas condenses from connecting the anode and the cathode of the bipolar electrode.