An exhaust gas purification device includes a first catalyst, a bypass pipe, a second catalyst, and a switching controller. The first catalyst is provided in an exhaust pipe. The bypass pipe branches from a first portion of the exhaust pipe. The first portion is located upstream of the first catalyst. The bypass pipe is recoupled to a second portion of the exhaust pipe. The second portion is located upstream of the first catalyst. The second catalyst is provided in the bypass pipe. The switching controller is configured to switch a flow path of an exhaust gas to the bypass pipe based on a deterioration degree of the first catalyst.