Abstract: A compression self-ignition engine is provided. The engine includes an engine body and an intake passage, and CI combustion is performable in a part of an engine operating range. The intake passage includes a high-temperature passage provided with a heater for heating intake air, a low-temperature passage provided with a cooler for cooling the intake air, a manifold section where the high-temperature and low-temperature passages merge together, and a downstream passage connecting the manifold section with the engine body. A throttle valve for adjusting a flow rate of the intake air is provided in each of the high-temperature and low-temperature passages. At least in an engine operating range where the CI combustion is performed, openings of the throttle valves are controlled to bring a temperature of the intake air within the manifold section into a predetermined temperature range, based on temperature conditions of the heater and the cooler, respectively.