A tuner apparatus 10 causes a user to designate a musical instrument that is to be tuned and a reference pitch that is a standard upon tuning, by a process at a setting portion 110. A pitch detecting portion 130 detects a pitch of a performed note inputted via a microphone 20 and input portion 120. A target note specifying portion 140 defines a note name, which is positioned nearest to the performed note in a predetermined temperament (e.g., 12-note equal temperament), as a target note based upon the detected pitch of the performed note and the inputted reference pitch. Then, a calculating portion 150 calculates a difference between the pitch of the performed note and the pitch of the target note, and a display control portion 160 causes the display device 30 to display the calculated difference. Further, the display control portion 160 converts the target note into a note name written in a score relating to the musical instrument to be tuned by using a transposition parameter relating to the musical instrument to be tuned that is stored in the storage portion 100 and set by the setting portion 110, and causes the display device 30 to display a staff in which a note corresponding to the note name written in a score is written.