PROBLEM TO BE SOLVED: To provide a medical basket type treatment instrument having excellent foreign material capture performance and enabling repeated capture and fracture of a foreign material to be performed.SOLUTION: In a medical basket type treatment instrument 2, when a length of respective basket wires 22a to 22d from a proximal end to a distal end tip of a basket part 22 along the basket wires is defined as LO, and a length of the respective basket wires 22a to 22d from the proximal end to a nearest inward bent part to the proximal end of the basket part 22 along the basket wires is defined as L1, 1/20&leL1/L0&le1/4 is satisfied. When a length from the nearest inward bent part to the proximal end to a nearest outward bent part of the basket part along a distal end direction along the respective wires is defined as L2, L1+L2 is equal to or larger than 1/2 of L0.
