PROBLEM TO BE SOLVED: To provide a marker capable of deciding an accurate excision line and confirmable with various diagnosis instruments, such as an ultrasonic wave, MRI, and computed tomography.SOLUTION: The surgery marker A is driven to a living tissue to decide a surgery area. The marker includes: a linear marker body A1 that has a prescribed length and is located in a marker center and a movement prevention section A2 that is located in a prescribed range of the marker body from a tip side to be inserted into the body toward a rear end side and prevents the marker body from moving in the insertion direction and a direction opposite to the insertion direction when the marker is driven to the inside of the body.
