Applications under a high confining pressure such as analysis a rock sample, etc. collected from the interior of an underground hole can be properly performed.
The pressure vessel 10 includes a tubular portion 100 and a cover portion 200 made of fiber reinforced plastics. The outer peripheral surface of an end portion 100a of the tubular portion 100 has a reverse-tapered shape of which the diameter is increased toward an end face 100b. The cover portion 200 includes a wedge-shaped member 202 installed along the reverse-tapered shape of the outer periphery surface of the end portion loon of the tubular portion 100, an outer ring 204 for covering the wedge-shaped member 202 from the outside, an inner ring 206 installed to cover an opening of the tubular portion 100 and the wedge-shaped member 202 and connected to the outer ring 204, and a sample cap 210 connected to the inner ring 206.