To provide a sample stage device which has a sample stage surface where a temperature gradient is formed and the temperature gradient can be intentionally controlled unlike conventional heaters for microscopes, since recently, it has been found out that nematomorph M and tick exhibit thermotaxic behavior.

A sample stage device 1 comprises the sample stage surface 31 where a sample is placed and a heating means for heating the sample stage surface 31. The heating means forms a desired temperature gradient in the sample stage surface 31. The temperature gradient is formed by using a transparent resistance heating film region 35 made of a single material and demarcating the transparent resistance heating film into small regions 39 having different temperatures by varying the separation distance between a pair of feeding electrodes.