A ratchet seat, a ratchet tool head, and a bidirectional ratchet hand tool are disclosed. A handle unit includes an annular groove and a cavity. A positioning ring is stretchably disposed in the annular groove. A first actuating unit and a second actuating unit are elastically placed one over another in the cavity. An outer peripheral surface of a ratchet seat forms a ratchet toothed portion and a positioning groove. The ratchet seat is movable between a first position and a second position in an up-down direction. When the first position is assumed, the positioning groove is slidably moved to engage with the positioning ring, and the first actuating unit meshes with the ratchet toothed portion. When the second position is assumed, the positioning groove disengages from the positioning ring, and the second actuating unit meshes with the ratchet toothed portion.