The hardness change amount (Hmax−Hbase) of the thick flexible tube portion 13 and the hardness change amount (HAmax−HAbase) of the thin flexible tube portion 13A are set so that the ratio to the base hardness is constant, respectively. The thicker the flexible tube portion, the larger the amount of change in hardness, and an endoscope with a relatively thin flexible tube portion also has a smaller amount of change in hardness. As a result, the endoscope with a thick flexible tube does not have insufficient hardness, and the flexible tube does not become too hard with a thin endoscope. Optimal insertion according to the thickness of the flexible tube Operation becomes possible. 太い可撓管部１３の硬度変化量（Ｈmax－Ｈbase）と、細い可撓管部１３Ａの硬度変化量（ＨＡmax－ＨＡbase）は、それぞれベース硬度に対する比率が一定となるように設定されており、可撓管部が太くなるほど硬度変化量が大きくなり、相対的に可撓管部が細い内視鏡は硬度変化量も小さくなる。これにより、可撓管部が太い内視鏡で硬さが不足し、また可撓管部が細い内視鏡で硬くなり過ぎるといったことがなく、可撓管の太さに応じた最適な挿入操作が可能となる。
