A video decoding method can comprise the steps of: acquiring image information from a bitstream, the image information including a picture header related to a current picture, and the current picture including a plurality of slices; parsing, from the picture header, a first flag indicating whether information necessary for an inter prediction operation is in the picture header and/or a second flag indicating whether information necessary for an intra prediction operation is in the picture header; parsing, from the picture header, the information necessary for the inter prediction operation and/or the information necessary for the intra prediction operation based on the first flag and/or the second flag; and generating prediction samples based on the information necessary for the inter prediction operation and/or the information necessary for the intra prediction operation.