Abstract: The present invention relates to a cap for being decorated with an assembly such as a block or toy, and more specifically the cap includes a base block plate (10) adhered to, detachably attached to, or assembled with the head covering part (3) or visor (5) of the cap for connecting with an assembly such as a decoration block or toy, wherein the base block plate (10) has an assembling part (15) for connecting with an assembly (20) such as a decoration block or toy in various forms and shapes for decoration, so as to provide profitable functions of decoration, use as a toy, and developing intelligence in addition to the head covering function.