An exhaust gas purification apparatus for a diesel engine mounted on a vehicle includes a regenerative diesel particulate filter, an accumulated amount detector, an exhaust gas temperature raising unit, and a forcible regeneration control unit. The forcible regeneration control unit measures an automatic regeneration enable time in which an automatic regeneration condition for regenerating the filter is satisfied when the diesel engine is operating, determines from the automatic regeneration enable time whether the probability is high in which a regeneration will be completed without being interrupted when the automatic regeneration condition is continuously satisfied, performs automatic regeneration when determining that the probability of regeneration being completed is high.