An apparatus includes: the arrangement pattern sampling data generator 111b for generating the arrangement pattern sampling; the bit pattern sampling data generator 111c for, each time process data are acquired from the controllers 51 to 5n, generating the bit pattern sampling; the calculator 111d for calculating the number-of-change-points threshold value indicating the threshold value for the number of process data each including the chronological change on the basis of the data size needed to store the elapsed times and the sampling cycles (the acquisition intervals) for the process data acquisition; and the storage controller 111a for storing any one of the bit pattern sampling data and the arrangement pattern sampling data, which requires a smaller storage capacity, into the storage unit 113.