To provide a retractor which is an operative field expanding instrument for intracardiac surgery to be used in a cardiac surgery performed endoscopically or under a surgery support robot, has such a structure that an optimum space for securing a visual field inside the heart can be maintained, has an automatic expansion type structure that can be deformed into a narrow shape when the retractor is to be inserted from a small port and can be returned to an original structure automatically after entering the body, and is formed of a soft material not damaging the heart.

The retractor is turned to the structure of indwelling a flexible tubular body around which a fully flexible tube 1 is spirally wound inside the heart. The retractor is made of a material such as Teflon(R), polyethylene, polypropylene, nylon, polyurethane or vinyl chloride. Thus, the surgery is quickly, accurately and easily performed, and the cardiac surgery can be safely performed even to an elderly person or a patient with highly severe disease.