An endoscope bending portion 7 includes a tubular member 40 provided with a treatment instrument channel 26 and a string guide 49 configured to hold wires 47 and 48, an interval t1 of a plurality of first slots 41 formed in a first tubular region 40a on a distal end side is made to be smaller than an interval t2 of a plurality of second slots 42 formed in a second region 40b at an intermediate portion, and a third interval t3 of a plurality of third slots 43 formed in a third tubular region 40c is also made to be smaller than the interval t2 of the plurality of second slots 42, and a dimensional ratio between a width w1 and the interval t1 of the first slots 41, a dimensional ratio between a width w2 and the interval t2 of the second slots 42 and a dimensional ratio between a width w3 and the interval t3 of the third slots 43 are equalized.
