This retractor easily ensures a surgical field as desired by an operator, can flexibly ensure and change the surgical field in accordance with the surgical site and the surgical situation, and can easily be moved to a desired position in the surgical site and taken out after the surgery. A retractor 1 holds a surgical incision in a body in an opened state to ensure a surgical field in small-incision endoscopic surgery, and includes a base body 2 that is a thin plate made of tin having a purity of not less than 99.9% and has an elongated rectangular shape in an extended state of the base body. The retractor 1, in an extended form in a rectangular shape or in a rounded form in a small shape, can be inserted from a small incision wound into the body, and can easily be delivered to the surgical incision in the body by a surgical instrument. The base body 2 is bent and deformed into a desired shape by the surgical instrument and is applied to the surgical incision in the body, so that the surgical incision can be held in an opened state so as to ensure the surgical field. The base body 2 is made of tin having a purity of not less than 99.9%, and thus the base body 2 has a high flexibility in particular, thereby allowing the base body 2 to be easily bent and deformed into a desired form by use of the surgical instrument.
