To provide a coring technique capable of preventing a core from coming off even in a super weak nature of soil containing much moisture, and capable of supporting sufficiently and recovering surely the core.

This coring device is formed with a double core barrel 3 provided rotatably with an outer assembly 1 in an outside of an inner assembly 2, and includes a core support bucket 22 extended upwards from an upper face of a ring body 22a held between a sleeve case 21 and an inner shoe 23, and formed with at least three or more of thin sheet elastic claws 22b, and each thin sheet elastic claw is formation-held in an inward bent state all the time, is elastically deformable to a vertically erected state erected vertically from the inward bent state, has an elastic force along a direction restored from the vertically erected state to the inward bent state, and is formed with an expandable film 29 to cover a clearance 22c between the adjacent thin sheet elastic claws.