Inorganic or organic particles have been used in the past as paper additives for hot-pressed forms to impart the pattern of granite thereto, but when these are boiled in hot water, for example, an uncountable number of small blisters result, lowering the commercial value of the product; however, according to the present invention it is possible to obtain an additive for forming patterns by grinding to desired particle sizes colored paper which has undergone water-resistance treatment with a thermosetting resin, and by selecting the color of the colored paper, a pattern may be selected as desired having spots of any desired color or size. With patterned paper manufactured by adding these paper additives during the paper manufacturing process, there is no occurrence of the above mentioned blisters and a clear pattern may be formed, and therefore hot-pressed forms utilizing have a natural granite image.