The ability to perform an unrehearsed piece of music, or sight-read, is a skill required by music performers. In sight-reading, the performer reads and plays the music simultaneously, which requires the coordination of visual, auditory, and motor processing. While performing, they display a characteristic called eye-hand span, in which the part of the score being looked at precedes the part being played. They must recognize, decipher, and process the score in the time between reading a note and playing it. An individual’s executive function (EF) that control their cognition, emotions, and behavior may be involved in overseeing these individual movements. However, no study has investigated how EF is related to the eye-hand span and performance during sight-reading. Therefore, the purpose of this study is to clarify the relationships among EF, eye-hand span, and piano performance. Thirty-nine Japanese pianists and college students aspiring to be pianists with an average of 33.3 years of experience participated in this study. They performed sight-reading of two types of music scores with different difficulty levels while their eye movements were measured using an eye tracker to obtain their eye-hand span. The core EFs of inhibition, working memory, and shifting, were measured directly for each participant. Piano performance was evaluated by two pianists who did not participate in the study. Structural equation modeling was used to analyze the results. The results showed that auditory working memory predicted eye-hand span (β = .73, p < .001 in easy score; β = .65, p < .001 in difficult score), and eye-hand span predicted performance (β = .57, p < .001 in easy score; β = .56, p < .001 in difficult score). Auditory working memory did not directly affect performance, but through eye-hand span. The eye-hand span for easy scores was significantly greater than that for difficult scores. Furthermore, in a difficult music score, the shifting ability predicted higher piano performance. These suggest that the input of notes from the eyes becomes sound in the brain and activates the auditory working memory, which is then transmitted to finger movement, resulting in piano performance. In addition, it was suggested that shifting ability is also needed to perform difficult scores.