A spinning controller has an arithmetic unit (18) and a controller (20). The arithmetic unit (18) establishes gate periods Tg for a pulse sequence signal (110) produced concomitantly with spinning of a sample tube (40) and obtains a count value (Ns) by counting the number of pulses falling within each gate period Tg. The arithmetic unit (18) has functions of finding differences in time from each gate period Tg to the pulse sequence signal (110) occurring around the starting point and ending point of each gate period Tg by making use of a high-speed clock signal (120) and of correcting the duration of the gate period Tg, based on the differences in time.