Provided is an AC LED light emitting device. The AC LED light emitting device flows a current to at least one AC LED array among at least two AC LED arrays of an AC LED light emitting unit to turn it on during one period of an AC power having sine wave characteristics if a magnitude of a voltage applied to the AC LED light emitting unit including at least two AC LED arrays each of which including at least one AC LED is smaller than a turn-on voltage determined according to the number of AC LED arrays of the AC LED light emitting unit. If the magnitude of the voltage applied to the AC LED light emitting unit is larger than the turn-on voltage of the AC LED light emitting unit, all of the AC LED arrays of the AC LED light emitting unit are turned on.