To provide the manufacturing method of a metal tubular body formed with a desired side hole regardless of its shape, position and number of pieces.

This method is to manufacture the metal tubular body having its inside diameter 2 mm or less and having the side hole. A plate body having a development shape of the tubular body and a notch part formed into a hole corresponding to the side hole of the tubular body and/or the side hole when press worked into the tubular shape are punched out from a metal thin plate and the plate body respectively with the metal thin plate and the plate body partially joined together. After the plate body is press worked into the tubular shape, the joining part between the metal thin plate and the plate body is cut and manufactured into the metal tubular body.