PROBLEM TO BE SOLVED: To provide a shutter structure that facilitates opening and closing without any trouble even if a tank side plate gets distorted due to push from grains in a grain tank in a shutter of a grain takeout port provided at the grain tank of a combine.SOLUTION: A grain tank 8 is provided for storing harvested grains, a grain takeout port 22 is provided at a tank side plate 8a of the grain tank 8 so as to take out stored grains, a plate-like shutter member 32 or 42 is provided so as to open and close the grain takeout port 22 by sliding, and a pair of rail members 33 and 34 or 43 and 44 is provided on the tank side plate 8a so as to support the shutter member 32 or 42 slidably. Each of the rail members 33 and 34 or 43 and 44 is formed of a member stronger than that of the tank side plate 8a and supports the shutter member 32 or 42 on sides of the rail members 33 and 34 or 43 and 44 slidably so as to prevent sliding contact with the tank side plate 8a.
