A direct-injection engine combustion chamber structure including, at a top surface of a piston, an inclined surface and an orthogonal surface. The inclined surface, continuous with an inner peripheral wall surface of a cavity, extends outward in a radial direction of the piston and becomes shallower toward an outer side in a radial direction of the piston. The orthogonal surface, continuous with an outer periphery of the inclined surface, without a gap, extends to an outer peripheral surface of the piston and is orthogonal to a central axis of the piston.