Engine exhaust emission purification device

A filter (1) collects particulates in an exhaust gas passage (22). The pressure loss of the filter (1) and the exhaust gas flow rate of the engine are detected, and an oil ash deposition amount on the filter is estimated. A filter regeneration determination value is set from the oil ash deposition amount and the exhaust gas flow rate. The filter regeneration timing is determined by comparing the differential pressure of this filter (1) with a regeneration determination correction value, and when it is determined that it is time to regenarate, the exhaust gas temperature is increased and regeneration of the filter (1) is performed. In this way, the filter regeneration timing is precisely determined regardless of the oil ash deposition amount, appropriate exhaust gas purification is performed, and impairment of fuel cost-performance is suppressed.