Correction of a non-invasive blood glucose measurement measured from a video image. Correction includes irradiating white light on the skin, filtering the white light reflected from the skin by a first wavelength filter and a second wavelength filter, obtaining a first signal including a blood glucose signal and a pulse signal based on a video image generated by the white light filtered by the first wavelength filter, obtaining a second signal including a pulse signal based on a video image generated by the white light filtered by the second wavelength filter, obtaining a blood glucose signal by subtracting the second signal from the first signal, and calculating the amount of blood glucose in a subcutaneous blood vessel based on the obtained blood glucose signal. Moreover, fundamental blood glucose signals can be extracted in real time without collecting blood.