A tubular medical instrument made of an alloy, comprising: one end portion, the other end portion, and a central portion, wherein the one end portion is a region including one axial end of the tubular medical instrument and having a length of 10% with respect to an axial length L 1 of the tubular medical instrument, the other end portion is a region including the other axial end of the tubular medical instrument and having a length of 10% with respect to the axial length L 1 of the tubular medical instrument, the central portion is a region including an axial center of the tubular medical instrument and having a length of 10% with respect to the axial length L 1 of the tubular medical instrument, and a ratio (difference V/difference W) calculated by the following test method is 3 or more: the tubular medical instrument is subjected to a contraction-expansion cycle where the tubular medical instrument is contracted from an expanded state to a contracted state such that an average diameter of the tubular instrument becomes 25%, and then allowed to expand from the contracted state to the expanded state, wherein the difference V is a difference between an expansion force per unit length in the radial direction in the central portion and an expansion force per unit length in the radial direction in the one end portion or the other end portion, whichever is smaller, at the time when the average diameter becomes 75% as the tubular medical instrument is being contracted from the expanded state such that the average diameter of the tubular instrument becomes 25%, and the difference W is a difference between an expansion force per unit length in the radial direction in the central portion and an expansion force per unit in the radial direction in the one end portion or the other end portion, whichever is smaller, at the time when the average diameter becomes 75% as the tubular medical instrument is being allowed to expanded from the contracted state. one end portion, the other end portion, and a central portion, wherein the one end portion is a region including one axial end of the tubular medical instrument and having a length of 10% with respect to an axial length L 1 of the tubular medical instrument, the other end portion is a region including the other axial end of the tubular medical instrument and having a length of 10% with respect to the axial length L 1 of the tubular medical instrument, the central portion is a region including an axial center of the tubular medical instrument and having a length of 10% with respect to the axial length L 1 of the tubular medical instrument, and a ratio (difference V/difference W) calculated by the following test method is 3 or more: the tubular medical instrument is subjected to a contraction-expansion cycle where the tubular medical instrument is contracted from an expanded state to a contracted state such that an average diameter of the tubular instrument becomes 25%, and then allowed to expand from the contracted state to the expanded state, wherein the difference V is a difference between an expansion force per unit length in the radial direction in the central portion and an expansion force per unit length in the radial direction in the one end portion or the other end portion, whichever is smaller, at the time when the average diameter becomes 75% as the tubular medical instrument is being contracted from the expanded state such that the average diameter of the tubular instrument becomes 25%, and the difference W is a difference between an expansion force per unit length in the radial direction in the central portion and an expansion force per unit in the radial direction in the one end portion or the other end portion, whichever is smaller, at the time when the average diameter becomes 75% as the tubular medical instrument is being allowed to expanded from the contracted state. the tubular medical instrument is subjected to a contraction-expansion cycle where the tubular medical instrument is contracted from an expanded state to a contracted state such that an average diameter of the tubular instrument becomes 25%, and then allowed to expand from the contracted state to the expanded state, wherein the difference V is a difference between an expansion force per unit length in the radial direction in the central portion and an expansion force per unit length in the radial direction in the one end portion or the other end portion, whichever is smaller, at the time when the average diameter becomes 75% as the tubular medical instrument is being contracted from the expanded state such that the average diameter of the tubular instrument becomes 25%, and the difference W is a difference between an expansion force per unit length in the radial direction in the central portion and an expansion force per unit in the radial direction in the one end portion or the other end portion, whichever is smaller, at the time when the average diameter becomes 75% as the tubular medical instrument is being allowed to expanded from the contracted state.