A combustion chamber for an internal-combustion engine of the direct fuel injection type using a volatile fuel having a low cetane number, such as alcohol. The combustion chamber comprises a main combustion chamber and an auxiliary combustion chamber which are formed in the crown of a piston so as to overlap each other and so that individual swirls of intake air are formed therein, respectively. The fuel highly atomized for quick evaporation is supplied to the auxiliary combustion chamber and fuel films are formed over the respective inner surfaces of the main and auxiliary combustion chambers for being vaporized by the heat of the walls of the main and auxiliary combustion chambers. Thus, the combustion chamber has excellent combustion characteristics, in which the air-fuel mixture is reliably ignited in the entire range of loaded operation of the engine, combustion noise and vibration are reduced, and the discharge of unburned substances is controlled.