Provided are a decorative sheet having stretchability and heat resistance and an in-mold forming method capable of forming in-mold injection formed products having excellent decorative image. A decorative sheet includes an image layer and an image running prevention region in order on a resin sheet, in which the image layer is a cured image of an ink composition containing (a) a polymerizable compound, (b) a polymerization initiator, and (c) a coloring agent; the image running prevention region is a cured layer of a composition for running prevention containing (a) a polymerizable compound, and (b) a polymerization initiator; and the image running prevention region has superior heat resistance to the image layer, and an injection forming method using the decorative sheet.