A spout apparatus for discharging hot or cold water with reciprocal motion at a variable amplitude, comprising: a spout apparatus main body; and an oscillation inducing element disposed in the spout apparatus main body for discharging supplied hot or cold water with a reciprocal motion from a spouting port; wherein the oscillation inducing element comprises: a water supply passageway into which water supplied from the spout apparatus main body flows; a water collision portion disposed on a downstream end portion of the water supply passageway so as to block a portion of a cross-section of the water supply passageway, the water collision portion alternately produces oppositely circulating vortexes on the downstream side of the water collision portion by colliding with hot or cold water guided by the water supply passageway; a vortex street passageway disposed on a downstream side of the water supply passageway for guiding and growing the vortexes formed by the water collision portion; and a discharge passageway disposed on a downstream side of the vortex street passageway for discharging water guided by the vortex street passageway; characterized in that a bypass passageway for causing hot or cold water supplied from the spout apparatus main body to flow into the vortex street passageway, detouring the water supply passageway and the water collision portion; and a flow volume ratio changing portion, capable of changing the flow volume ratio between hot or cold water flowing into the vortex street passageway through the water collision portion and hot or cold water flowing into the vortex street passageway through the bypass passageway. a spout apparatus main body; and an oscillation inducing element disposed in the spout apparatus main body for discharging supplied hot or cold water with a reciprocal motion from a spouting port; wherein the oscillation inducing element comprises: a water supply passageway into which water supplied from the spout apparatus main body flows; a water collision portion disposed on a downstream end portion of the water supply passageway so as to block a portion of a cross-section of the water supply passageway, the water collision portion alternately produces oppositely circulating vortexes on the downstream side of the water collision portion by colliding with hot or cold water guided by the water supply passageway; a vortex street passageway disposed on a downstream side of the water supply passageway for guiding and growing the vortexes formed by the water collision portion; and a discharge passageway disposed on a downstream side of the vortex street passageway for discharging water guided by the vortex street passageway; characterized in that a bypass passageway for causing hot or cold water supplied from the spout apparatus main body to flow into the vortex street passageway, detouring the water supply passageway and the water collision portion; and a flow volume ratio changing portion, capable of changing the flow volume ratio between hot or cold water flowing into the vortex street passageway through the water collision portion and hot or cold water flowing into the vortex street passageway through the bypass passageway. a water supply passageway into which water supplied from the spout apparatus main body flows; a water collision portion disposed on a downstream end portion of the water supply passageway so as to block a portion of a cross-section of the water supply passageway, the water collision portion alternately produces oppositely circulating vortexes on the downstream side of the water collision portion by colliding with hot or cold water guided by the water supply passageway; a vortex street passageway disposed on a downstream side of the water supply passageway for guiding and growing the vortexes formed by the water collision portion; and a discharge passageway disposed on a downstream side of the vortex street passageway for discharging water guided by the vortex street passageway; characterized in that a bypass passageway for causing hot or cold water supplied from the spout apparatus main body to flow into the vortex street passageway, detouring the water supply passageway and the water collision portion; and a flow volume ratio changing portion, capable of changing the flow volume ratio between hot or cold water flowing into the vortex street passageway through the water collision portion and hot or cold water flowing into the vortex street passageway through the bypass passageway.