Method of agitating solution

A method of stirring a solution for contacting a selective binding substance immobilized on a surface of a carrier with a solution containing an analyte substance reactive with the selective binding substance, comprising the steps of:

• adding fine particles into the solution,
• sealing the fine particles in the solution with a seal and the carrier, and stirring the solution by moving the fine particles sealed in the solution by using the carrier and/or a container which have a convex-concave structure such that the fine particles do not contact the selective binding substance-immobilized surface, wherein
• (i) the carrier has a convex-concave structure and the selective binding substance is immobilized on the top face of the convexes, and a minimum width of the fine particles is greater than a minimum distance between the selective binding substance-immobilized surface and the container, and/or
• (ii) the container for the solution has a convex-concave structure, the selective binding substance is immobilized on the carrier under the container convexes, and a minimum width of the fine particles is greater than a minimum distance between the selective binding substance-immobilized surface and the container convexes.