A duty cycle correction (DCC) circuit and a delayed locked loop (DLL) circuit using the same are disclosed. The DCC circuit is operated by an enable signal which is enabled when the DLL is locked. The duty cycle correction (DCC) circuit includes a clock input unit and a duty cycle mixing unit. The clock input unit receives the enable signal and first and second clock input signals having opposite phases, generates an inverting signal of the first clock input signal, and when the enable signal is enabled, generates first and second internal clock signals, based on the first and second clock input signals and the inverting signal. The duty cycle mixing unit mixes a phase of the first internal clock signal with a phase of the second internal clock signal.