We report a significant complication that occurred during double guidewire insertion. The first guidewire (GW1) was inserted under ultrasonographic guidance, whereas the second guidewire (GW2) was inserted by the landmark-based method. Subsequently, GW2 penetrated and entangled with GW1, which caused difficulty in removing both guidewires. A dilator was used to dilate the puncture site, allowing simultaneous removal of both guidewires with minimal invasion. The first guidewire was found to be pointing in a cranial direction, indicating the manner in which the second guidewire's puncture needle had penetrated it. Thus, when double cannulation is performed, guidewire position should be confirmed.