Provided is an indwelling catheter that is hard when a vessel such as a blood vessel is inserted, becomes soft after the indwelling of the vessel, and adapts to a shape along the running direction of the vessel. The maximum value of the repulsive force of a catheter in a dry state at 25 ° C. is 0.10 N or more, and the maximum value of the repulsive force of a catheter when immersed in warm water at 37 ° C. is 0.01 to 0.25 N. The ratio of the maximum value of the catheter repulsion force in a dry state at 25 ° C. to the maximum value of the catheter repulsion force at the time of immersion in warm water is 3.5 or more, and the maximum value of the catheter repulsion force at the time of immersion at 37 ° C. is 5 An indwelling catheter that is less than or equal to 0.027N after minutes. [Selection diagram] None【課題】血管などの脈管挿入時では硬く、脈管留置後は柔軟化し、かつ脈管走向に沿った形状に馴染む留置カテーテルを提供する。【解決手段】２５℃の乾燥状態におけるカテーテル反発力の最大値が０．１０Ｎ以上であり、３７℃の温水浸漬時におけるカテーテル反発力の最大値が０．０１～０．２５Ｎであり、３７℃の温水浸漬時におけるカテーテル反発力の最大値に対する２５℃の乾燥状態におけるカテーテル反発力の最大値の比が３．５以上であり、３７℃の温水浸漬時におけるカテーテル反発力の最大値が留置５分後に０．０２７Ｎ以下である、留置カテーテル。【選択図】なし
