Disclosed is a particulate filter regenerating system which comprises a fuel injection device (7) adapted to inject fuel into a combustion chamber of an engine body (1), and an exhaust gas temperature-adjusting device (33) adapted, when a PM deposit amount which is an amount of particulate matter (PM) deposited in a DPF (particulate filter) 13 provided in an exhaust passage of an engine, reaches a predetermined value X, to cause the fuel injection device (7) to perform a post-injection for injecting fuel into the combustion chamber during an expansion stroke of the engine, so as to execute a filter regeneration process of raising a temperature of exhaust gas flowing into the DPF 13 to burn the deposited PM. The exhaust gas temperature-adjusting device (33) is operable to cause the fuel injection device (7) to stop performing the post-injection in a stage where a PM burning amount which is an amount of PM burned through the filter regeneration process, is less than an initial PM deposit amount which is the PM deposit amount X at a timing of initiation of the filter regeneration process, by a predetermined amount. The particulate filter regenerating system of the present invention can adequately burn and remove PM deposited in a particulate filter, by means of a post-injection of fuel, while effectively suppressing a fuel consumption due to the post-injection.