The tuning device also includes an input unit for inputting a sound of an instrument to be tuned or a musical sound signal, a conversion information storing portion in which a plurality of pieces of information on filters for tuning are stored, a control unit for extracting the piece of information on an arbitrary one of the filters from the conversion information storing portion, and a conversion unit for converting a signal of the input unit into a signal of an arbitrary frequency band in response to a signal from the control unit. Owing to this structure, even if ambient noise has mixed with a sound of the instrument to be tuned, the sound is filtered into a signal component of a target scale or a target pitch name. By extracting a pitch from this signal component, the number of erroneous tuning operations can be reduced.