A fluidic device includes: a circulation flow path; and a capture part arranged on the circulation flow path and configured to capture a sample substance in a solution and/or a detection part arranged on the circulation flow path and configured to detect a sample substance in a solution. A method of capturing a sample substance that is bound to a carrier particle, using a fluidic device which includes a circulation flow path and a capture part arranged on the circulation flow path and configured to capture the carrier particle and in which the circulation flow path has two or more circulation flow path valves, includes: an introduction step of, in a state where the circulation flow path valve is closed, introducing a solution that includes a sample substance to at least one of partitions partitioned by the circulation flow path valve and introducing a solution that includes a carrier particle which is bound to the sample substance to at least another of the partitions; a mix step of opening all of the circulation flow path valves and circulating and mixing a solution in the circulation flow path; and a capture step of capturing the carrier particle by the capture part.