To provide a flexible frame member and a through hole making method using the member for the use for foundation work for reinforced concrete building.

This member comprises a flexible balloon body 1 and a flexible and tubular cover 2 covering the balloon main body 10 of the balloon body 1. The balloon body 1 secures the flexible frame member comprising the expandable and contractable balloon main body, a compressed contraction type foldable inlet/outlet passage 12 extending outside desired length from a position near at least one end of the tubular body 10d of the balloon main body 10 and a compressed contraction type check passage 11 communicating the inlet/outlet passage 12, extending to and communicating the inside of the balloon main body 10 and having a function to check introduced fluid.