PURPOSE: To obtain the title device capable of extending the life of a saw blade and achieving the reduction of vibration while enhancing usability by setting off the cutting resistances, by using an endless type saw blade and allowing two track parts of the saw blade to approach each other in an almost mutually overlapped state by a guide means.

CONSTITUTION: When a housing 10 is grasped and a switch 17 is turned ON, a motor 12 is rotated in a definite direction and the rotation thereof is transmitted to a drive pulley 1 through a gear box 13. Since a saw blade 3 is of endless type, when the pulley 1 is rotated in a fixed direction, both track parts 3a, 3b of the saw blade 3 run in directions reverse to each other as shown by arrows (a), (b) and, therefore, the cutting reaction forces in the running direction of the saw blade 3 are set off and the total length of the saw blade 3 can be effectively used in cutting and the life thereof becomes long and the generation of vibration due to reciprocating movement is eliminated and cutting operation is performed without feeling tired.