A pitch estimating method and apparatus in which mixture Gaussian distributions based on candidate pitches having high period estimating values are generated, a mixture Gaussian distribution having a high likelihood is selected and dynamic programming is executed so that the pitch of the speech signal can be accurately estimated. The pitch estimating method comprises computing a normalized autocorrelation function of a windowed signal obtained by multiplying a frame of a speech signal by a window signal and determining candidate pitches from a peak value of the normalized autocorrelation function of the windowed signal, interpolating a period of the determined candidate pitches and a period estimating value representing a length of the period, generating Gaussian distributions for the candidate pitches for each frame for which the interpolated period estimating value is greater than a first threshold value, mixing the Gaussian distributions which are located at a distance less than a second threshold value to generate mixture Gaussian distributions and selecting at least one of the mixture Gaussian distributions that a likelihood exceeding a third threshold value, and executing dynamic programming for the frames to estimate the pitch of each frame, based on the candidate pitches of each of the frames and the selected mixture Gaussian distributions.