Abstract: A gas purifying device has a re-circulating section configured to re-circulate liquid discharged from an element positioned on a downstream side of an airflow to reflow to a liquid circulation system path of an element positioned on an upstream side of the air flow. The liquid dissolves and removes low-concentration contaminants by gas-liquid contact. The liquid is discharged from the element on the downstream side and is made to reflow to the element on the upstream side through the re-circulating section. Contaminants are dissolved and removed by gas-liquid contact between the liquid and non-purified air containing high-concentration contaminants.