A lavage device includes a housing unit, a power module, a transmission unit and an irrigation unit. The housing unit includes a housing body that defines a receiving space having an opening, and a cover that covers openably the opening. The power module is disposed in the receiving space, and is removable from the receiving space via the opening when the cover is opened. The power module includes a motor. The transmission unit includes a driven gear coupled to and driven rotatably by the motor, and a push member driven to reciprocate by the driven gear. The irrigating unit is connected to the transmission unit, and is adapted for drawing liquid through the reciprocate action of the push member and performing irrigation.
