PURPOSE: To reduce the capacity of a memory for storing a sound signal such as a musical sound signal, etc. containing many periodic signals by dividing the sound signal into a periodic component and a non-periodic component by using a filter, and encoding and storing each of them.

CONSTITUTION: An input signal is divided into a periodic component XP and a non-periodic component XA by filters HP, HA, encoded and compressed by encoders EP, EA, respectively, and written on a memory M. By a separation of these components, as for a sound signal such as a musical sound signal, etc. containing many periodic components, the compression is raised as a whole, and the capacity of the memory is reduced.