1. An information processing apparatus comprising: an acquisition device connectable to a server by way of a network to acquire one or more distributed keywords; a central processing unit to determine an importance level of each keyword acquired by the acquisition device, wherein, when the respective keyword is registered, the central processing unit calculates the importance level the respective keyword by subtracting a time difference value from a number of occurrences of the respective keyword, in which the time difference value is equal to a predetermined value times a difference between a current time and a last acquisition time of the respective keyword, and wherein, when a result of subtracting the time difference value from the number of occurrences of the respective keyword is negative, the importance level of the respective keyword is set to zero, and wherein, when the respective keyword is not registered, the central processing unit sets the importance level of the respective keyword to one; extraction means for extracting text information of a subtitle included in a program; subtitle morphological analysis means for performing morphological analysis on the text information of the subtitle; comparison means for comparing each keyword acquired by the acquisition device with each keyword detected via the morphological analysis performed by the subtitle morphological analysis means; recording means for recording the program if the comparison performed by the comparison means indicates that any keyword acquired by the acquisition device is identical to any keyword detected via the morphological analysis performed by the subtitle morphological analysis means; and registration means for registering, in a table, the program recorded by the recording means and information indicating the importance level in association with the keyword.
7. The information processing apparatus according to claim 1 , in which the predetermined value is 0.5.