An endoscope bending portion includes a tubular member provided with a treatment instrument channel and a string guide configured to hold wires, an interval of a plurality of first slots formed in a first tubular region on a distal end side is made to be smaller than an interval of a plurality of second slots formed in a second region at an intermediate portion, and a third interval of a plurality of third slots formed in a third tubular region is also made to be smaller than the interval of the plurality of second slots, and a dimensional ratio between a width and the interval of the first slots, a dimensional ratio between a width and the interval of the second slots and a dimensional ratio between a width and the interval of the third slots are equalized.