To provide a sampling frequency converter that is especially compatible with a plurality of sampling frequencies and applicable to applications where restriction is placed on an arithmetic quantity and a data quantity.

The sampling frequency converter for digital acoustic signal data is provided with an IIR(Infinite Impulse Response) filter that limits a frequency band of the digital acoustic signal data, a polynomial interpolation section that converts the sampling frequency of the digital acoustic signal data into a prescribed sampling frequency through polynomial interpolation, and a phase management section that initializes input and output phases by each prescribed period depending on the sampling frequency before the conversion and the sampling frequency after the conversion in order to maintain a cross- reference between the input and output phases by the sampling frequency conversion.