An oral irrigator contains: a body, a water tank and a detachable jet tip which are both in connection with the body, a power device and a control device Which are both accommodated in the body. The power device is configured to deliver water from the water tank to the detachable jet tip. The power device includes a first outlet defined thereon and configured to discharge the water, a delivery tube connecting with the first outlet, and a first seal element configured to stop water flowing into the body from the power device so that the water discharges out of the first outlet.