PURPOSE: To make a user irrespectively of a beginner or veteran can comfortably play a keyboard so as to make a high-level musical expression by forming all keys of the keyboard to the same length, width, height and cross section, and at the same time, the upper section of each key to an almost semicircular shape, with the highest point being along the center line in the width direction of the key.

CONSTITUTION: Keys CWG, A, and B are white keys and keys C#, Eb, F#, Ab, and Bb are black keys as in the case of conventional one, but all of the white and black keys are formed to the same length, width, height, and cross section. Moreover, the upper section of each key is formed to an almost semicircular shape, with the highest point being along the center line in the width direction of the key. Since the upper section of each key is formed to the semicircular shape, no special trouble and difficulty are felt at the time of playing a piano, and even in the case of a beginner, he can touch the piano string striking center of each key. In addition, only one pattern of finger order is required at the time of transposition. Therefore, musical performances of transposition and transfer can be practiced comfortably.