Provided is a catheter retaining tool (10a) comprising a piercing tool (11), a guide wire (12) and an operation means (22). The piercing tool (11) includes a Y-hub (14), an outer needle (20), an indwelling needle (30) and a syringe (16). The Y-hub (14) includes a main port (40), an obliquely connected side port (42), and a hemostatic valve (44) for keeping the side port (42) liquid-tight. The guide wire (12) is inserted by the operation means (22) from the side port (42) through the hemostatic valve (44) into the outer needle (20). The operation means (22) includes a turning portion (76) made rotatable relative to the side port (42) and having a hollow portion (92), an extending portion (78) connected to the turning portion (76), and a slide portion (80) for pushing out the guide wire (12) along the extending portion (78). The turning portion (76) includes a first rolling spindle (82) and a second tilting spindle (84).
