A puncture adapter includes a guide of a puncture needle, a gripper to hold an ultrasound probe, and a pinch. The gripper grips the ultrasound probe. The puncture adapter is attached to the ultrasound probe by the engagement between the gripper and the ultrasound probe. The pinch is used to release the grip of the gripper. The pinch is located adjacent to the gripper in a direction that intersects a direction in which the gripper grips the ultrasound probe.