1. A comment recording apparatus including a voice input device and a voice output device for recording and playing back comment voice, the comment recording apparatus comprising: a voice obtaining unit to obtain comment voice, delivered by participant, as voice data using the voice input device, and to register the obtained voice data to a voice database for each topic specified by a topic specification device from among a plurality of topics registered in a topic database in advance, and each comment-delivered participant identified from the voice data; a voice recognition unit to conduct a voice recognition process on the voice data registered in the voice database to obtain text information; a morphological analysis unit to conduct a morphological analysis on the text information obtained by the voice recognition unit, and to register a keyword extracted from words obtained by the morphological analysis unit to a keyword database with topic and comment-delivered participant registered to the voice database along with voice; and a display generation unit to display the keyword in a matrix while relating the keyword to a topic and a comment-delivering participant, wherein when a current comment is delivered while the topic is changed from one topic specified by the topic specification device to another unrelated topic, the display generation unit separately displays a keyword obtained from new voice data for the another unrelated topic in a specific area in the matrix.