The practical effect of the inoculative release of the predatory mite Amblyseius swirskii Athias-Henriot against thrips on broad bean was evaluated in commercial farmer fields. Experiments were conducted at six different fields from October to December in 2019 in Ibusuki City, Kagoshima, Japan. The dominant species of thrips was Thrips hawaiiensis（Morgan）. The population densities of thrips when A. swirskii was released were significantly lower throughout experiment and decreased by approximately 35% on average compared to the control （non-treatment） trials in the five fields. However, the predatory mites were not effective in one field. Differences in the densities of predatory mites on broad bean might affect the efficacy. Further research is required to improve the efficacy and success of biological control for broad bean.