To eliminate temperature rise and noise due to the generation of electromagnetic noise and rotation, to lessen mechanical minute vibration from a driving source, and to enable a low price and miniaturization of equipments by making unnecessary a power source for the driving source of a rotor.

A magnet 9 is fixed to a rotor 7 having plural paddles, and the rotor 7 is rotated by fluid 3, and a sample cell 14 is installed adjacent to the rotor 7, and also an agitating element 16 for magnetic materials floated in the sample cell and the magnet 9 of the rotor 7 are connected and rotated by magnetic force, thereby the contents in the sample cell are agitated.