Abstract: This invention relates to a digital sound data storing device wherein analog sound data is synthesized from digital sound data. The device includes a case and an IC card detachably attached to the case. A plurality of digitized sound data groups are stored at a built-in memory of the IC card. The digitized sound data groups are obtained by recording sentences for foreign language conversation practice through a microphone to thereby obtain analog sound signal which is converted to digital sound signal. When the IC card is attached to the case, a signal processing circuit operates to read out the digital sound data group, which is converted to the analog sound signal. The analog sound signal is supplied to an amplifying circuit and reproduced as sound.