PURPOSE: To provide a multicylinder two-cycle engine to reduce the number of processes through reduction of the weight of a labyrinth seal and reduction of the number of fine grooves for seal and facilitate execution of measurement of run-out of a crank shaft.

CONSTITUTION: In a multicylinder two-cycle engine wherein crank shafts 5 between a plurality of cylinders are continued to each other, labyrinths 15 and 15 fitted in the crank shaft 5 between the cylinders comprise two members in a form that the labyrinth is divided into two sections by a direction crossing the axis of the labyrinth at right angles. A distance part 17 is arranged between the labyrinth seals 15 and 15 and fitted the around the crank shaft 5.