The invention provides a clock generating circuit for generating a spectrum spread clock and carrying out high-speed and accurate phase control of a reference clock signal and an output clock signal, which is composed of compact circuits, and a method for generating the clock. The spectrum spread clock generating circuit 1 is provided with a phase comparator unit 10 that compares the reference clock signal CLKS with the internal clock signal in terms of a phase difference, and outputs a control current IC1 in compliance with the result of comparison; a clock generating unit 20 for generating an output clock signal CLKO; a phase difference signal modulating unit 30 for outputting a control current IC3; and a delay unit 40 for delaying the output clock in compliance with the control current IC3 and outputting the internal clock signal CLKN.