Engine supercharging system

The present invention relates to an engine supercharging system and is intended to sufficiently fulfill the supercharging function at the time of either of low speed running of the engine and high speed running and realizing output improvement or fuel expense reduction. The present invention has the engine (101) having the jet mechanism for directly jetting fuel into the cylinder (101a), the first turbo supercharger (104) for supercharging the engine (101) at the time of low speed rotation, the second turbo supercharger (105) for supercharging at the time of high speed rotation, the first and second exhaust control valves (106 and 107) for selecting exhaust paths relating to the first and second turbo superchargers (104 and 105) and controlling the exhaust gas flow rate.