Determining a cache hit ratio of a caching device analytically and precisely. There is provided a cache hit ratio estimating apparatus for estimating the cache hit ratio of a caching device, caching access target data accessed by a requesting device, including: an access request arrival frequency obtaining section for obtaining an average arrival frequency measured for access requests for each of the access target data; an access request arrival probability density function generating section for generating an access request arrival probability density function which is a probability density function of arrival time intervals of access requests for each of the access target data on the basis of the average arrival frequency of access requests for the access target data; and a cache hit ratio estimation function generating section for generating an estimation function for the cache hit ratio for each of the access target data on the basis of the access request arrival probability density function for the plurality of the access target data.