To decrease a noise following cooling of a motor of a chain saw and discharge of chips.

A motor (7) for driving a saw chain (6) and a cooling fan (15) for sending cooling wind to the motor (7) are provided in a housing (1). A space between the saw chain (6), the motor (7) and the cooling fan (15) is partitioned with a partition (21) integrated with the housing (1). A chips discharging hole (22) is provided to a bottom part of the housing (1) corresponding to an end part of a cutting travelling route (6b) of the saw chain (6). A wind window (18) for blowing out an exhaust of the cooling wind toward the saw chain (6) is provided to an upper part of the partition (21). By composing the cooling fan (15) of a centrifugal fan, a noise generated following air-sending is decreased.