Exhaust purification system

An exhaust purification system comprising:

• an oxidation catalyst provided in an exhaust passage of an internal combustion engine;
• a filter provided in the exhaust passage at a position 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 oxidation catalyst;
• an accumulation amount estimating unit configured to estimate an amount of accumulated particulate matter in the 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 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.