To evaluate and conserve the biodiversity of tidal flats, quantitative research studies and precise identification of benthos species are required. However, there has been no convenient procedure for conducting a benthos survey by common people attempting the conservation of tidal flat ecosystems. In this paper, we describe our attempts to make a civil procedure with a method that is not only simple but also semi-quantitative and analytical. From field tests and field practices, we propose the following method as the civil procedure. At least 8 people are necessary for this work, which entails collecting epifauna during a 15-min search and infauna from 15 holes dug with a small scoop. After collection, the benthos species are identified in the fields through the help of experts and by referring to a handy-sized guidebook with pictures of benthos species. Then, the benthos species are recorded by checking on the tidal flat benthos check sheet. Next, numbers of the check marks for respective species recorded on every check sheet are transcribed to a new sheet (to ascertain how many people collect each species). The total number of species recorded on this combined sheet signifies species richness, with >70% check mark recorded being evaluated as dominant, 70–10% as common and <10% (or collected by only 1 person) as a rare species. Since the civil procedure is designed to be conducted by more than 8 people, deviations due to personal idiosyncrasies would be eliminated. Therefore, the civil procedure we proposed would be not only simple and easy for beginners but also semi-quantitative and analytical. It might be possible to make significant comparisons with other tidal flats and it might be prove useful for long-term monitoring by the public.