PURPOSE: To ensure fillet freed from rib to be obtained, by providing a conventional equipment for three fillet cut with a ribremoving mechanism.

CONSTITUTION: Belts 3, 3 are extended backward, the front end of a fish body guide saddle 4 approaches its rear end followed by inserting the saddle 4 into the gap of the above extended portion, thereby a rib-carrying fillet 22-pressing plate 16 formed with a three fillet cut mechanism 7 is allowed to stand so as to be slidable back and forth, and the left and right sidewall surfaces of the rear of this plate 16 are made into tapered ones 17, 17 so as to be narrower at the rear when viewed from above. A fillet 22holding gap is kept nearly in parallel with the belt 3, 3 sections and also between such sections from the left and right sidewall surfaces of the plate 16 before the tapered surface 17 to backwardly project fillet-sliding guide plates 18, 18. Furthermore, a cutter 21 fitted with rotary circular edges 20, 20 on both the left and right ends of the shaft is installed between the guide plates 18, 18 so as to enable the rear end of the plate 16 to be inserted between the fronts of both the circular edges 20, 20. The guide plates 18, 18 located at the tapered surfaces 17, 17 and both the left and right sides of the front of both the circular edges 20, 20 are provided with windows 19, 19 for pushing the rib-carrying fillet 22 thereinto, respectively, and also provided with pressing members 24, 24 for pushing into the guide plate 18, 18 sides the belt 3, 3 sections located at the left and right sides of the front of both the windows 19, 19.