To manufacture a vessel of which the bottom and the side wall have almost the same wall thickness.

A forming station 13 and a heating station 12 are provided and the heating station 12 has two plates 18, 18a and 19, 19a so movable as to proceed to each other and to come into contact with a belt-shaped sheet 2. At least one of the two plats is formed to be heatable and at least one plate 18, 19 of the two has a first region 21 disposed with a narrower space to the belt-shaped sheet 2 than other regions 22 and 23 of the plate. When the two plates 18 and 19 are moved toward each other, the belt-shaped sheet 2 is subjected to plastic deformation by the effects of heat and pressure and the material of the belt-shaped sheet 2 is thereby pushed aside to the other regions 22 and 23 from the first region 21.