The invention provides a method of producing an amorphous alloy ribbon, the method including a step of producing an amorphous alloy ribbon by discharging a molten alloy through a rectangular opening of a molten metal nozzle having a molten metal flow channel along which the molten alloy flows, the opening being an end of the molten metal flow channel, onto a surface of a rotating chill roll, in which, among wall surfaces of the molten metal flow channel, a maximum height Rz(t) of a surface t, which is a wall surface parallel to a flow direction of the molten alloy and to a short side direction of the opening, is 10.5 μm or less.