A power tool comprises a driving mechanism and a gear housing space (105a) which houses the driving mechanism. A lubricant is provided to the driving mechanism inside a gear housing (105). The driving mechanism includes a driving motor (110) having a motor shaft (111). The motor shaft (111) includes an inner communicating opening (191), an outer communicating opening (192) and an air passage (193) which connects the inner communicating opening (191) and the outer communicating opening (192). At least a part of the air passage (193) is arranged inside the motor shaft (111), and the passage (193) communicates with the gear housing space (105a) via the inner communicating opening (191) and also communicates with the outer space of the gear housing (105) via the outer communicating opening (192).