Abstract: A propeller power transmission device according to the present invention comprises an input shaft 9 connected to a drive shaft 7 of an engine 3 via a coupling 8; a pair of right and left output shafts 12 and 13 connected to the right and left propeller shafts 5 and 6 via couplings 10 and 11, respectively; a gear train comprised of gears 20 to 30 for transmitting the power of the input shaft 9 to each of the output shafts 12 and 13 through clutch mechanisms 14, 15, 16 and 17, and causing the output shafts to undergo forward or reverse rotation in response to switching between forward and reverse rotation clutch mechanisms; and a gear case 4 for containing the input shaft 9, the output shafts 12 and 13, the gear train of gears 20 to 30, and the forward and reverse rotation clutch mechanisms 14 to 17.