An atrial appendage ligation surgical tool that includes: a tubular loop shaft having an inner hole that penetrates therethrough in a longitudinal direction and a ligature loop that is in an inserted state in the inner hole of the loop shaft and formed of a wire that forms a loop closed with a knot at a distal end of the loop shaft, the loop being contractible in size by being pulled from a proximal end of the loop shaft. The ligature loop is given a tendency to form a flat ring-shaped loop having a size an atrial appendage is insertable when in a free state, and the knot is placed near an end of the loop in a long axis direction thereof.
