A picture signal processing method and apparatus, a picture signal recording method and apparatus, and a recording medium, in which resolution switching is effected seamlessly. To this end, a controller 19 has the function of reading out the identification information specifying the resolution of the bitstream and the relation between the recording units, from a user data region provided in a video stream as a minimum unit which permits switching of the resolution in a MPEG 2 standard bitstream, and of switching the resolution of the picture signals associated with the recording units.