Abstract: The present invention provides a sheath for gastrostoma (1), a sheathed dilator, a gastrostomy catheter kit and a method of splitting a sheath for gastrostoma. The sheath for gastrostoma (1) includes a sheath body (11) in which a gastrostomy catheter (2) is inserted and a handle (12). The sheath for gastrostoma (1) lowers the insertion resistance of a gastrostomy catheter when inserted in a fistula before insertion of the gastrostomy catheter in the fistula for replacement in the patient's body. According to the invention, a sheath for gastrostoma, a sheathed dilator, a sheath for gastrostoma with insertion aid, a gastrostomy catheter kit and a method of splitting a sheath for gastrostoma which can lower the insertion resistance during placement of a catheter in the patient's body, facilitate air supply control of an endoscope and stabilize endoscopic visual field during surgery are provided.