A mold for a pneumatic tire which contains a pair of bead portions, a pair of sidewall portions and a tread portion provided with a tread pattern formed by repeating a pattern unit around the tire at plural kinds of pitches in a sequence, wherein the mold includes a sidewall molding surface for one of the sidewall portions, and a tread molding surface provided with a negative tread pattern formed by repeating the negative pattern unit at the above-mentioned plural kinds of pitches in order to mold the tread pattern. The sidewall molding surface contains sector regions defined as extending radially inwardly from the pattern units, respectively, wherein the largest sector regions are defined as extending from the pattern units with the largest pitch swells towards a cavity of the mold, when compared with the smallest sector regions which are defined as extending from the pattern units with the smallest pitch. The amount of swelling is such that the larger the pitch, the larger the amount of swelling.