In an inspection device in which a leakage of He gas from a product 1 is detected when He gas is pressurized and charged into the product 1 accommodated in a vacuum chamber 2, a variable displacement means, capable of changing the volume of the vacuum chamber corresponding to a size of the product 1, is provided in the vacuum chamber. A transport protocol is provided that improves video data throughput under such conditions. The light spots traverse across the tracks in one of a first direction and a second direction. In one example, the opening is provided on a belt. Also, little Ir andor IrO2 diffuses through the bottom electrode to the ferroelectric elements, and therefore there is little risk of damage to the ferroelectric material.