PURPOSE: To reduce passage resistance and disperse stress concentration by disposing a thick-walled part, satisfying a specific condition, on the inside of a bent part, disposing shift parts of specific length on both sides of the thick- walled part, and forming the outer peripheral shape of the bent part into almost the same shape as an element pipe.

CONSTITUTION: A metallic bent pipe 30 has a bent part of R≤D/2 and θ=60-120°, where R is a bend inner radius, θ is a bending angle. and D is the outer diameter of the metallic pipe. In this case, a thick-walled part 31 satisfying the following condition is disposed at the inner surface of the bending angle θpart on the inside of the bent part, whereas shift parts 31-1, 31-2 of wall thickness gradually approaching the wall thickness of the element pipe and 1/D or more in length are disposed on both sides of the thick-walled part 31, and the outer peripheral shape of the bent part is formed into almost the same shape as the element pipe, that is, 2.0t≥T2≤1.5t, where T2 is the inner wall thickness (mm) of the bending angle θ part, and (t) is the wall thickness (mm) of the element pipe. The passage resistance of a fluid is thereby reduced, and the stress concentration of the bent part is dispersed.