A knock control apparatus for internal combustion engine includes: a knock signal normalization unit that normalizes a knock signal extracted from an output signal of a knock sensor; a knock determination threshold setting unit that sets a knock determination threshold on the basis of the normalized knock signal; a knock intensity computation unit that calculates knock intensity on the basis of the normalized knock signal and the set knock determination threshold; a knock determination unit that determines a presence or absence of a knock on the basis of the calculated knock intensity; and a knock correction amount computation unit that calculates a knock correction amount to correct the calculated knock intensity in a case where an occurrence of a knock is determined. The knock signal normalization unit normalizes a standard deviation of the knock signal by dividing the knock signal by an average value of the knock signal.