PROBLEM TO BE SOLVED: To solve the problems that, since a first flow-down guide plate is constituted separately from an external side plate, a shaking separation shelf has poor strength, and that, since a separation net is integrated with the shaking separation shelf body, maintenance of the periphery of a first conveyor is difficult to be performed in the state where the shaking separation shelf body is mounted on a threshing machine.SOLUTION: A shaking separation shelf 20 under a threshing chamber 11 has a transfer shelf part 22, a sieve 23 and a straw rack 30, and is formed of a synthetic resin material. A body unit 51 in which a first flow-down guide plate 40 for guiding downflow of grains to a first conveyor 32 under the shaking separation shelf 20 is formed integrally with an external side frame 63 of the shaking separation shelf 20, and an inner unit 52 having the sieve 23 and a separation net 31 are constituted separately. A threshing machine is constituted so that the separation net 31 and a part of the first flow-down guide plate 40 are overlapped in a plane view in the state where the inner unit 52 is mounted on the body unit 51.
