A selection device includes a storage unit and a selection unit. The storage unit stores the write time and the read time of each of a plurality of nodes. The selection unit selects a first response condition in response to a data write request on the basis of the write time of each of the plurality of nodes such that the response time for the data write request becomes shorter than a requirement value of the write time and the number of nodes in which writing has been completed increases. The selection unit selects a second response condition in response to a data read request on the basis of the first response condition and the read time of each of the plurality of nodes such that the response time for the data read request becomes shorter than a requirement value of the read time.