Two-cycle engine and engine work machine

A two-cycle engine, comprising a structure where, through descending of a piston, a mixed gas guided into a crank case is guided into a combustion chamber formed on an upper side of the piston through a scavenging passage, wherein the crank case is disposed to a lower side of the piston performing a reciprocal up-down movement in a cylinder, wherein in the two-cycle engine,

• a notch part is formed locally from a lower end side on a sidewall part of the piston sliding along an inner surface of the cylinder, the notch part is connected to the scavenging passage when the piston is located at a bottom dead center, a crank case protruding part is disposed in the crank case, and the crank case protruding part is located on a lower side of the scavenging passage and penetrates through the notch part and protrudes toward a central axis side of the cylinder when the piston is located at the bottom dead center.