Herein disclosed is a function-variable type DSP apparatus comprising: a storage section for storing a plurality of DSP microprogram parts; and a plurality of DSP executing sections each for executing the DSP microprogram parts to implement a DSP function, each of the DSP microprogram parts being executable by each of the DSP executing sections to perform a set of steps necessary to implement a DSP base function forming part of a DSP function, whereby the DSP executing sections are operative to receive the DSP microprogram parts simultaneously from the storage section, and selectively execute the DSP microprogram parts in a sequence to respectively implement desired DSP functions.