PURPOSE: To form a flexible metallic cylinder of any size easily by forming a cylinder material providing a recess part for fitting opening to outside on an edge of a metallic flat plate and making a thickened part for fitting on the other edge and fitting the thickened part to the recess groove winding the cylinder material into spiral form.

CONSTITUTION: An adjoining recess groove 2 which is opened to outer side is formed in a body by bending on an edge of a belt-like flat plate 1 made of elastic metallic material. A cylindrical thickened part 3 that can be inserted into the recess groove 2 is formed in a body by bending on the other edge to form a long cylinder material. The cylinder material 4 is rolled to spiral form and adjoining recess groove 2 and thickened part 3 are fitted to desired depth to form a flexible metallic cylinder. By this way, working efficiency can be improved remarkably.