Described herein is a combustion chamber for internal combustion engine, including a protuberance extending radially inward from a peripheral wall surface of a combustion chamber which is formed by hollowing the top of a piston in the axial direction thereof. The protuberance induces rolling streams turning in the same direction as the fuel swirl thereby collecting air and atomized fuel in a region on the upstream side of the protuberance. The rolling stream serves to improve the ignition quality by enriching the concentration of fuel vapors in that locality. The flames generated in the vicinity of the protuberance are propagated to the atomized fuel which is supplied to other regions of the combustion chamber, thereby providing an internal combustion engine with improved ignition and combustion qualities.