An exhaust gas purification device (6) comprises: first and second catalyst carriers (21, 22) interposed in an exhaust passage (8) of an engine (1), which purify an exhaust gas; a case (20) provided in the exhaust passage, which houses the first and second catalyst carriers (21, 22) in series in an exhaust gas flow direction; an annular carrier holder (24) interposed between the first and second catalyst carriers (21, 22), which holds the first and second catalyst carriers (21, 22) via a buffering member (23) and has an opening (34) which connects an inner peripheral side and an outer peripheral side; a sensor (10) which detects the state of the exhaust gas flowing through the interior of the case (20); and a sensor attachment portion (26) provided in the case (20), which connects the interior and exterior of the case (20) in an orientation that is substantially orthogonal to the exhaust gas flow direction. The sensor attachment portion (26) is provided in a position corresponding to the opening (34) when the carrier holder (24) is housed in the case.