Even in a case where an amount-of-reflected-light distribution of a surface is locally different, in order to measure a distance with high accuracy, at least one embodiment of a distance measurement apparatus includes an image acquisition unit configured to acquire a first captured image obtained by capturing a measurement target object onto which a measurement pattern is projected, and a second captured image obtained by capturing the measurement target object irradiated with approximately uniform illumination, a smoothing filter determination unit configured to, based on the second captured image, determine a smoothing filter to be applied to the first captured image, a smoothing filter application unit configured to apply the smoothing filter determined by the smoothing filter determination unit to the first captured image, and a measurement unit configured to measure a distance from the measurement target object based on the first captured image to which the smoothing filter is applied.