An engine comprising a particulate filter which is arranged in the exhaust passage and has a function of absorbing NOx, where the amount of discharged particulate discharged from the combustion chamber per unit time is made smaller than the amount of particulate removable by oxidation per unit time without emitting a luminous flame on the particulate filter and where the temperature of the particulate filter is maintained in a temperature range where the NOx absorption rate becomes more than a certain value.