According to one embodiment, the method of manufacturing a semiconductor device includes contacting a film formed on a semiconductor substrate with a rotating polishing pad which is supported on a turntable, and feeding polishing foam to a region of the polishing pad with which the film is contacted, thereby polishing the film. The polishing foam is obtained by turning the aqueous dispersion into a foamy body. The aqueous dispersion includes 0.01-20% by mass of abrasive grain and 0.01-1% by mass of foam forming and retaining agent, all based on a total mass of the aqueous dispersion.