PURPOSE: To detect assuredly an access fault of a voice memory by providing a blank area between the voice message information store areas of the voice memory and detecting a read-out action from said blank area.

CONSTITUTION: A voice memory reading control part 4 reads out data successively at and after the head address of the corresponding store area for voice message information of a voice memory 2 based on the access information indicated by a response control part 3. A fault detecting part 8 counts the number of '0' data and performs nothing before the count value CNT reaches the limit value α. While the part 4 repeats the reading action of the next data. when the value CNT reaches the value α, the part 8 issues information to the part 3. The part 3 has no fault any more.