In an engine combustion chamber, a first intake port (19) formed from a straight port has a throat portion (43) formed in a linear shape and opening in a tangential direction of the inner periphery of a cylinder (11a), thus generating a first swirl (S1), and a second intake port (20) formed from a helical port has a throat portion (44) formed in a helical shape, thus generating a second swirl (S2) inside the first swirl (S1) in the same direction as that of the first swirl (S1). In this way, even with the first and second intake ports (19, 20) hardly curved overall, it is possible to efficiently generate first and second swirls (S1, S2) that do not interfere with each other, and it becomes possible to reduce the cost of machining the cylinder head, make the cylinder head compact, and simplify the structure of the cylinder head.