PROBLEM TO BE SOLVED: To provide a medical valve body having satisfactory styptic, smaller resistance when an insertion object is inserted and withdrawn, superior operability, and effectively suppressing the end of the insertion object from being crashed, and to provide a medical insertion assisting tool.SOLUTION: The medical valve body includes an elastic valve body 45 having an adhesive hole 46 formed thereon to be through from an inlet face 41 to an outlet face 43. A dilator body 8 can be inserted and withdrawn through the adhesive hole while liquid-tight property is being maintained. A plurality of guide grooves 42 are radially formed in a circumferential direction as the center of the adhesion hole 46 in the inlet face 41 of the valve body 45 on a side, into which the dilator body 8 is inserted.
