A subjective quality estimating part (11) receives an undeteriorated reference video signal (RI) and a deteriorated video signal (PI) produced from the reference video signal, calculates video signal feature values for both the signals, and according to a difference between the calculated video signal feature values of the signals, estimates a subjective quality of the deteriorated video signal. A feature value calculating part (12) calculates the video signal feature values of the reference video signal. A correction information storing part (13) stores correction information that corresponds to video signal feature values and is used to correct the subjective quality. A correction calculating part (14) receives the video signal feature values of the reference video signal from the feature value calculating part (12), retrieves correction information corresponding to the received video signal feature values from the correction information storing part (13), and transfers the retrieved correction information to a correcting part (15). According to the transferred correction information, the correcting part (15) corrects the subjective quality estimated by the subjective quality estimating part (11).