An endoscope set comprising: an endoscope; a sheath for covering the endoscope, the sheath having a light-transmissive window formed at the tip end thereof, a bending instrument attached to the tip end of the sheath for causing in use the tip end portion of the endoscope to bend, said bending instrument for an endoscope being characterized in that the bending instrument is provided with: a fixed part which is fixedly attached to the outer periphery of the sheath at the tip end thereof such that the fixed part cannot move towards the base end of the abovementioned sheath; a sliding part which is slidably attached further towards the base end of the abovementioned sheath than the portion where the abovementioned fixed part is attached; a flexible linking part for joining the abovementioned fixed part and the abovementioned sliding part; and a deformable cylindrical spacer which is fitted on the outer periphery of the abovementioned sheath between the abovementioned fixed part and the abovementioned sliding part; and a gastrostomy catheter which has a tubular part formed with an internal through-hole, and a part adapted to be fixed to the inner side of the stomach which is joined to the tip end of the abovementioned tubular part in a state in which the tip end of the through-hole of the abovementioned tubular part is open and which is provided with an engaging part in the vicinity of the tip end of the abovementioned through-hole, the whole of the abovementioned bending instrument for an endoscope being insertable into the abovementioned through-hole, and the sliding part of the abovementioned bending instrument for an endoscope being engageable with the engaging part of the abovementioned stomach-internal fixed part adapted to be fixed to the inner side of the stomach. an endoscope; a sheath for covering the endoscope, the sheath having a light-transmissive window formed at the tip end thereof, a bending instrument attached to the tip end of the sheath for causing in use the tip end portion of the endoscope to bend, said bending instrument for an endoscope being characterized in that the bending instrument is provided with: a fixed part which is fixedly attached to the outer periphery of the sheath at the tip end thereof such that the fixed part cannot move towards the base end of the abovementioned sheath; a sliding part which is slidably attached further towards the base end of the abovementioned sheath than the portion where the abovementioned fixed part is attached; a flexible linking part for joining the abovementioned fixed part and the abovementioned sliding part; and a deformable cylindrical spacer which is fitted on the outer periphery of the abovementioned sheath between the abovementioned fixed part and the abovementioned sliding part; and a gastrostomy catheter which has a tubular part formed with an internal through-hole, and a part adapted to be fixed to the inner side of the stomach which is joined to the tip end of the abovementioned tubular part in a state in which the tip end of the through-hole of the abovementioned tubular part is open and which is provided with an engaging part in the vicinity of the tip end of the abovementioned through-hole, the whole of the abovementioned bending instrument for an endoscope being insertable into the abovementioned through-hole, and the sliding part of the abovementioned bending instrument for an endoscope being engageable with the engaging part of the abovementioned stomach-internal fixed part adapted to be fixed to the inner side of the stomach. a fixed part which is fixedly attached to the outer periphery of the sheath at the tip end thereof such that the fixed part cannot move towards the base end of the abovementioned sheath; a sliding part which is slidably attached further towards the base end of the abovementioned sheath than the portion where the abovementioned fixed part is attached; a flexible linking part for joining the abovementioned fixed part and the abovementioned sliding part; and a deformable cylindrical spacer which is fitted on the outer periphery of the abovementioned sheath between the abovementioned fixed part and the abovementioned sliding part; and a gastrostomy catheter which has a tubular part formed with an internal through-hole, and a part adapted to be fixed to the inner side of the stomach which is joined to the tip end of the abovementioned tubular part in a state in which the tip end of the through-hole of the abovementioned tubular part is open and which is provided with an engaging part in the vicinity of the tip end of the abovementioned through-hole, the whole of the abovementioned bending instrument for an endoscope being insertable into the abovementioned through-hole, and the sliding part of the abovementioned bending instrument for an endoscope being engageable with the engaging part of the abovementioned stomach-internal fixed part adapted to be fixed to the inner side of the stomach.