Part units of speech information are arranged in a predetermined order to generate a sentence unit of a speech information set. To each of a plurality of speech part units of the speech information, an attribute of “interrupt possible after reproduction” with which reproduction of priority interrupt information can be started after the speech part unit of the speech information is reproduced or another attribute of “interrupt impossible after reproduction” with which reproduction of the priority interrupt information cannot be started even after the speech part unit of the speech information is reproduced is set. When the priority interrupt information having a high priority rank than the speech information set being currently reproduced is inputted, if the attribute of the speech information being reproduced at the point in time is “interrupt impossible after reproduction,” then the priority interrupt information is reproduced after the speech information is reproduced.