An apparatus, method, and medium for detecting an impact sound and an apparatus, method, and medium for discriminating the impact sound using the same. The impact sound detecting apparatus includes: an onset detector separating an input signal of a frame unit into a low frequency signal and a high frequency signal, measuring powers of the separated signals, and detecting onsets by detecting changes in the measured powers; an event buffer buffering the powers measured by the onset detector and spectral data of the input signal; and an impact sound verifier determining whether each of the detected onsets is an impulse onset, and if each of the detected onsets is the impulse onset, detecting events starting from the impulse onsets by checking the powers stored in the event buffer and determining each of the detected events to be an impulse event if each of the detected onsets satisfies a predetermined condition.