A sampling function generator capable of providing continuous output corresponding to a sampling function. The sampling function generator 1 comprises a B spline function generation circuit 10, delay circuits 12 and 14, inverting amplifiers 16 and 18, and adding circuits 20 and 22. The B-spline function generation circuit 10 continuously produces signal waveforms according to a third order B spline function. After delayed by predetermined time or attenuated to 1/4 amplitude and inverted, the signal waveforms are combined in the adding circuits 20 and 22 to form a signal waveforms of a sampling function that is differentiable once over the range and has values of local support.