An accordion includes a right hand play side, a left hand play side, a bellow, four rows of buttons, and two rows of buttons. The four rows of buttons include a first column to which first continuous four pitches are assigned, a second column to which second continuous four pitches are assigned, and a third column to which third continuous four pitches are assigned. The two rows of buttons include a first column to which first continuous two pitches are assigned, the first continuous two pitches being continuous from or to the first continuous four pitches, a second column to which second continuous two pitches are assigned, the second continuous two pitches being continuous from or to the second continuous four pitches, and a third column to which third continuous two pitches are assigned, the third continuous two pitches being continuous from or to the third continuous four pitches.