“Compose” combines an electronic pen and a music book. Compose can create music by singing into its electronic pen. After the pen is inserted back into the music book, musical notation will be shown immediately so as to increase the efficiency of music writing. Vice versa, professional music note written in the music score by the input pen can be converted into music, raising the efficiency of the creative composer. It also features the voices of several musical instruments. According to the user's setting, the device can perform the same melody by different musical instruments.