The present invention pertains to a sized product, which contains a drug, polyethylene oxide with a molecular weight of 2,000,000 or higher, and a specific size controlling agent for polyethylene oxide (substance with the appropriate plasticity and binding force) and wherein at least the above-mentioned specific size controlling agent is uniformly dispersed in the above-mentioned polyethylene oxide, a controlled-release pharmaceutical composition containing this sized product, and a method of manufacturing a controlled-release pharmaceutical composition containing this sized product.A controlled-release pharmaceutical composition with good uniformity of content can be presented by using powder particles of polyethtylene oxide with powder properties suitable for tableting, which is obtained by uniform dispersion of the specific size controlling agent for polyethylene oxide of the present invention.