To provide a self-sealing type flexible seal capable of being closely attached to the inner wall flexibly even when the inner diameter of a tube is changed, and an intratubular moving body provided with the self-sealing type flexible seal.

In the self-sealing type flexible seal for intratubular surface sealing including two hollow bowl-like seal member A and seal member B which are formed of a flexible material, are annularly opened at two pole parts facing each other and form figures similar to each other, the seal member A is arranged on the outer side and the seal member B is arranged on the inner side in the state that two sheets are stacked and closely attached, the seal member A and the seal member B both have N pieces of slit parts of similar figures extending from the vicinity of one opening to the vicinity of the other opening, and for a phase angle formed by the seal member A and the seal member B, on a surface orthogonal to the same axis of the seal member A and the seal member B, is arranged such that a phase is shifted with the axis as the center.