In this paper, we will propose a picture quality scale PQS vs for video, applying the objective evaluation values of picture quality of still pictures for each frame of the monochrome video. This is an evaluation method based on the mean opinion score (MOS), which is obtained from the subjective evaluation of the picture quality when each frame of the video is considered as a still picture. First, for a video in which one sequence consists of 150 frames, a subjective evaluation experiment is carried out and the MOS is determined for several distinctive frames, and then the picture quality evaluation scale PQS still2 of the still picture is prepared. For the estimation methods of the MOS from 150 evaluation values of PQS still2 , we have studied the method of using the worst value of the short-interval average of PQS still2 and the method of estimating the MOS from the linear multiple regression of average value and worst value of PQS still2 . From these methods, high-accuracy estimation of MOS can be performed for the video whose picture quality evaluation values are stable throughout the sequence.