The data acquisition unit acquires data in correspondence with each dimensional axis and the time axis. The mode setting unit makes setting and clearing of a dimensionality investigation mode. In the dimensionality investigation mode, the axis-determinative variation-rate calculation unit calculates axial data variation rates. The axis determination unit determines whether or not the axial data variation rate corresponding to each axis is low. The objective-axis setting unit sets each axis as an objective axis when the axial data variation rate corresponding to the axis is determined to be high. While the dimensionality investigation mode is cleared, the recording-determinative variation-rate calculation unit calculates axial data variation rates. The recording determination unit determines, on the basis of the axial data variation rate, whether to record the acquired data. The recording unit does not record the data when the data is determined not to be recorded.