A mechanism for collecting a trace of a biological sample to be used for a biological sample analysis, and for preparing a diluted solution of the sample. A container for specimen preparation includes: a biological sample collecting device; and a container for sample dilution. The biological sample collecting device includes: a capillary tube having openings formed at both ends thereof; and a support member for supporting the capillary tube. The container for sample dilution includes: an opening; and a swirl flow generating member formed on an inner wall of the container for sample dilution. The capillary tube of the biological sample collecting device is arranged inside the container for sample dilution by the support member.