Engine rotation speed controller for working machine

A rotation speed controller of an engine for working machine which has manual operation means of a throttle opening of the engine and adjusts an engine rotation speed according to a load by the manual operation means, comprising:

• a first rotation control characteristic in which an ignition device of the engine is operated in a region in which the throttle opening is small at a first ignition timing so as to increase the engine rotation speed from an idle rotation speed with increase of the throttle opening;
• a second rotation control characteristic in which the ignition device is operated in a region in which the throttle opening is large at a second ignition timing on the advance side than the first ignition timing so as to increase the engine rotation speed steeper than that of the first rotation control characteristic with increase of the throttle opening;
• and
• switching means for determining the first ignition timing or the second ignition timing switched to each other based on the engine rotation speed, wherein
• in the decrease process of the engine rotation speed, the switching means switches the second ignition timing to the first ignition timing at an engine rotation speed higher than that switched to the second ignition timing in the increase process.