PURPOSE: To enhance the efficiency in the inspection of a plastic container, by a method wherein a container to be inspected is inserted between an external electrode and an internal electrode having plural needles planted therein and a high voltage current is applied between both electrodes to carry out discharge if a pinhole is present.

CONSTITUTION: An external electrode 1 having a concaved cavity 2 into which a container A to be inspected can be inserted formed thereto and an internal electrode 3 manufactured so as to be coincided with the shape of the container A to be inspected and having plural needles 5 planted in the surface of the electrode main body 4 thereof are provided. In inspection, the container A to be inspected is inserted between both electrodes and a high voltage current is applied. If the container A to be inspected has a pinhole B, discharge is carried out between the needle 5 nearest to said pinhole B and the external electrode 1 and the inferior container is instantaneously determined. By this method, the detection of the inferior container is certainly performed and the inspection efficiency can be enhanced to a large extent.