In a method of moulding a sole of a plastic material and a welt on a shoe upper (1) a mould (3) is used. The mould (3) includes at last (2), upon which a shoe upper (1) is arranged, an upper mould part (5) divided along a longitudinal middle plane and thus includes two halves (5a, 5b) being laterally movable in relation to the lower mould part (4) between an open and a closed mould position, and a lower mould part (4) being vertically movable in relation to the upper mould part (5) between an open and a closed mould position. For carrying out the method an annular shoe welt (6) is provided and arranged in the mould in the mould's open position. The two halves (5a, 5b) of the upper mould part (5) are closed and the lower mould part is moved into its closed position. As a result a circumferential support surface (7) on the upper face of the lower mould part (4) co-acts with a pressure surface (17) on the lower face of a projection (15) on each half (5a, 5b) of the upper mould part such that the portion of the welt (6) facing the shoe upper (1) it tilted inwards and downwards to bring the inner end face of the welt (6) into sealing engagement with the lower side section of the shoe upper (1). The shoe sole is then moulded in a manner known per se by supplying a plastic material to the cavity of the mould.