PROBLEM TO BE SOLVED : To allow more accurate search of real estate property information to be provided to a guest on the basis of voices of the guest and a host.SOLUTION : An H/G determination part 41 identifies voices of a host and a guest who are seated at different positions on the basis of intensity of detection sounds by directional microphones 22 to 25 whose sound collecting directions are freely adjustable. Question keywords and answer keywords of each of the types of questions classified with one or more question keywords are registered in a keyword table 45. A keyword determination part 44 determines which of the registered question keywords is included in the identified voice of the host and the type of the question based on the question keyword, determines which of the registered answer keywords corresponding to the type of the latest question is included in the identified voice of the guest, and makes a keyword for search storage part 46 store the determined answer keyword in association with the type of the question.