A horizontal rotary hook for a sewing machine includes an inner bobbin case holder accommodating a bobbin, an outer rotating hook accommodating the bobbin case holder and rotated in a predetermined direction with the bobbin case holder being accommodated in the rotating hook, the rotating hook having an outer peripheral wall formed with a bobbin-thread passing opening through which the bobbin thread passes, an enlarged opening defined in the outer peripheral wall of the rotating hook so as to be continuous to the bobbin-thread passing opening, a beak member separate from the rotating hook and mounted on the rotating hook so as to close the enlarged opening, and a fitting holder mounted on the rotating hook so that a lower part of the beak member is fitted into the fitting holder, thereby holding the beak member.