An exhaust gas purification device is disposed in an exhaust passage of an engine disposed in an engine room defined in a hull, and is configured to remove at least a nitrogen oxide from an exhaust gas discharged from the engine. The exhaust gas purification device includes: a catalytic part including a selective reducing catalyst for selectively reducing the nitrogen oxide; a reducing agent addition device configured to add a reducing agent to the exhaust gas on an upstream side of the catalytic part in a flow direction of the exhaust gas; and a casing configured to contain the catalytic part. At least a part of the casing is disposed inside the engine room.