A duty cycle error accumulation circuit includes first to nth delay units and a feedback unit. The first to nth delay units receive a clock signal, a first input signal and a second input signal, respectively, to generate a first output signal and a second output signal by delaying one signal selected from first and second input signals based on a logic level of the clock signal. The feedback unit supplies second input signal to a kth delay unit based on second output signal of a (k+1)th delay unit. The first output signal of the kth delay unit is supplied to the (k+1)th delay unit as first input signal, and the clock signal is supplied to the first delay unit as first input signal and to the nth delay unit as second input signal. The duty cycle error accumulation circuit effectively corrects a duty cycle of a clock signal.