Exhaust purification system

An exhaust purification system comprising:

• an oxidation catalyst provided in an exhaust passage of an internal combustion engine;
• a pair of first and second filters provided in the exhaust passage at positions downstream of the oxidation catalyst to collect particulate matter contained in exhaust gas;
• an electrostatic capacity detecting unit configured to detect an electrostatic capacity of the first filter;
• an accumulation amount estimating unit configured to estimate an amount of accumulated particulate matter at least in the second filter based on the electrostatic capacity entered from the electrostatic capacity detecting unit;
• and
• a filter regenerating unit configured to execute a forced regeneration to burn and remove the particulate matter that has accumulated at least in the second filter by injecting fuel to the oxidation catalyst when the amount of accumulated particulate matter entered from the accumulation amount estimating unit exceeds a predetermined amount.