1. An information processing apparatus, comprising: means for acquiring program information for received contents; means for extracting keywords from the program information; means for counting the number of occurrences for each of the extracted keywords to obtain a keyword count for each of the extracted keywords; means for storing the keyword counts; means for computing respective difference values for each of the extracted keywords by subtracting a prior keyword count stored by the storing means from a current keyword count; means for extracting predetermined keywords from the program information based on the difference values; means for searching program information including the predetermined keywords extracted by the second extracting means; and control means for controlling a display unit to display a list of the program information uncovered by the searching means together with a list of the predetermined keywords extracted by the second extracting means, a user may select a displayed keyword to display a list of programs related to the selected keyword, each of the prior keyword counts is generated by counting occurrences of the corresponding keyword for a respective first predetermined period of time, and each of the current keyword counts is generated by counting occurrences of the corresponding keyword for a respective second predetermined period of time, such that each difference value represents a difference between the number of occurrences of a keyword during a second predetermined period of time and the number of occurrences of the keyword during a first predetermined period of time, the keywords extracted by the second extracting means excluding keywords included in an excluded keyword dictionary, and the keywords extracted by the second extracting means being a predetermined number of keywords determined according to the difference values as ranked in descending order, such that the rank of any keyword extracted by the second extracting means is higher than the rank of any keyword not extracted by the second extracting means.