The hybridization device of the invention aims to attain a hybridization reaction of high reproducibility. A hybridization device 2 for a hybridization reaction of nucleic acid has a cover member 10 that defines a cavity 12, which includes a nucleic acid fixation area 6 of a substrate 4 for fixation of a nucleic acid probe and has capacity for storage of a liquid for the hybridization reaction therein. At least part of an area exposed to inside of the cavity 12 forms a hydrophobic region 18. Adequate control of the surface characteristic of the area exposed to the cavity for implementing the hybridization reaction desirably enhances the signal intensity and reduces a variation in signal intensity, thus attaining the hybridization reaction of high reproducibility.