A storage controlling apparatus includes a processor, wherein the processor: controls a first counter configured to count, among data stored in a cache memory and relating to an access request, a number of data which are not written in storage volumes of a target of the access request, for each storage volume; determines, in response to reception of a first access request, whether or not a first ratio of a counter value of the first counter to a number of data allocated already to the cache memory into a first storage volume exceeds a first threshold value, the counter value of the first counter corresponding to the first storage volume which is a target of the first access request; and performs a write back process of data from the cache memory into the first storage volume where the first ratio exceeds the first threshold value.