The indwelling device for embolization has a proximal side and a distal side in order to securely fix the extension suppressing member (20) by the coil portion (11), and includes a lumen in the longitudinal direction. A coil portion (11) and an extension suppressing member (20) arranged in the lumen are included, fixed in a lumen proximal to the coil portion (11), and a proximal end of the lumen. It has a connecting structure in which the stretch suppressing member (20) is connected to a rod-shaped detaching portion extending more proximally.塞栓形成用体内留置具は、伸張抑制部材（２０）をコイル部分（１１）により確実に固定するために、近位側および遠位側を有し、長軸方向に渡って管腔を備える前記コイル部分（１１）と、前記管腔内に配置される前記伸張抑制部材（２０）を含み、前記コイル部分（１１）の近位部の管腔内に固定され、前記管腔の近位端より近位側に延びる棒状の離脱部に、前記伸張抑制部材（２０）を結んだ結合構造を有する。
