A loop flow type bubble generation nozzle (10, 20, 30, 40, 50) comprising: a loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56) that is configured to stir and mix liquid and gas by a loop-like flow to form a fluid mixture; a liquid feed hole (5a, 25a, 35a, 45a, 55a) formed on one end of the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56), the liquid feed hole (5a, 25a, 35a, 45a, 55a) being configured to feed pressurized liquid to the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56); at least one gas inflow hole (3, 23, 33, 43, 53) into which gas can flow; a gas feed chamber (4, 24, 34, 44, 54) formed on the other end side of the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56), the gas feed chamber (4, 24, 34, 44, 54) being configured to feed gas flowing in through the at least one gas inflow hole (3, 23, 33, 43, 53) to the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56) toward one end side of the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56) through the entire circumference or part of the circumference while circulating the gas around a central axis of the liquid feed hole (5a, 25a, 35a, 45a, 55a); a jet hole (8a, 28a, 38a, 48a, 58a) formed on the other end of the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56) in a manner to align a central axis of the jet hole (8a, 28a, 38a, 48a, 58a) with the central axis of the liquid feed hole (5a, 25a, 35a, 45a, 55a), the jet hole (8a, 28a, 38a, 48a, 58a) having a diameter larger than the diameter of the liquid feed hole (5a, 25a, 35a, 45a, 55a) and being configured to jet the fluid mixture from the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56); and a tapered section (7, 27, 37, 47, 57) whose diameter continuously expands from the jet hole (8a, 28a, 38a, 48a, 58a) toward the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56), characterized in that at least one cut-away part (7a, 27a, 37a, 47a, 57a) is formed on an end of the tapered section (7, 27, 37, 47, 57), the end facing the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56). a loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56) that is configured to stir and mix liquid and gas by a loop-like flow to form a fluid mixture; a liquid feed hole (5a, 25a, 35a, 45a, 55a) formed on one end of the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56), the liquid feed hole (5a, 25a, 35a, 45a, 55a) being configured to feed pressurized liquid to the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56); at least one gas inflow hole (3, 23, 33, 43, 53) into which gas can flow; a gas feed chamber (4, 24, 34, 44, 54) formed on the other end side of the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56), the gas feed chamber (4, 24, 34, 44, 54) being configured to feed gas flowing in through the at least one gas inflow hole (3, 23, 33, 43, 53) to the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56) toward one end side of the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56) through the entire circumference or part of the circumference while circulating the gas around a central axis of the liquid feed hole (5a, 25a, 35a, 45a, 55a); a jet hole (8a, 28a, 38a, 48a, 58a) formed on the other end of the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56) in a manner to align a central axis of the jet hole (8a, 28a, 38a, 48a, 58a) with the central axis of the liquid feed hole (5a, 25a, 35a, 45a, 55a), the jet hole (8a, 28a, 38a, 48a, 58a) having a diameter larger than the diameter of the liquid feed hole (5a, 25a, 35a, 45a, 55a) and being configured to jet the fluid mixture from the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56); and a tapered section (7, 27, 37, 47, 57) whose diameter continuously expands from the jet hole (8a, 28a, 38a, 48a, 58a) toward the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56), characterized in that at least one cut-away part (7a, 27a, 37a, 47a, 57a) is formed on an end of the tapered section (7, 27, 37, 47, 57), the end facing the loop flow type gas-liquid stirring and mixing chamber (6, 26, 36, 46, 56).