To provide a tapered can forming method capable of preventing generation of wrinkles or steps.

In the metallic tapered can having an inverted conical side wall part with the diameter of an opening part being larger than the diameter of a bottom part, the taper angle exceeds 1.5°, the height of the can is larger than the diameter of the opening part of the can, and the side wall part has an annular thick-walled portion having the predetermined width in the vertical direction with the large wall thickness. Since the thick-walled portion of the large wall thickness is annularly formed on the side wall part with the predetermined width in the vertical direction, the strength of the side wall part is increased by increasing the size of the entire side wall part by increasing the thickness of a metal plate before the forming. Thus, by using the material of small thickness, the strength similar to that of the formed tapered can is maintained, and the cost is reduced. In particular, the strength of the side wall part can be increased in the tapered can in which the can height easy to deform the side wall part is larger than the diameter of the opening part.