An acid-gas capturing apparatus according to an embodiment includes an absorption unit configured to discharge an absorption-unit exhaust gas, and a regeneration unit configured to discharge a regeneration unit exhaust gas. The regeneration unit exhaust gas is compressed in a compression unit. The absorption-unit exhaust gas or the regeneration unit exhaust gas before it is compressed by the compression unit is cleaned in a first cleaning unit by means of a first cleaning liquid. A compression-condensate liquid, which is generated by the compression of the regeneration unit exhaust gas in the compression unit, is mixed into the first cleaning liquid through a first compression-condensate-liquid line whose one end is connected to the compression unit.