A ratchet wrench includes a head rotatably receiving a drive member. The head includes an end wall having a hole. One of an inner face of the end wall and an end face of the drive member defines a first abutment face. The other of the inner face and the end face includes an annular groove having a bottom wall defining a second abutment face. A dustproof ring is mounted and compressed in the annular groove. The dustproof ring in an uncompressed state has a natural maximum height along a rotating axis of the drive member larger then a spacing between the first and second abutment faces. The dustproof ring includes three sealing units along a radial direction perpendicular to the rotating axis. Each sealing unit has a thickness along the rotating axis smaller than the spacing.