An exhaust purification device comprising: a filter provided in an exhaust system of an internal combustion engine and collecting particulate matter in exhaust gas; a first sensor provided upstream of the filter in an exhaust direction of the exhaust gas and including: a first sensor filter having a plurality of first cells divided by porous partition walls and collecting the particulate matter in the exhaust gas to be introduced into the filter; and at least one pair of first electrodes (32A, 33A) arranged to face each other with the first cell interposed therebetween so as to form a capacitor; a second sensor provided downstream of the filter in the exhaust direction of the exhaust gas and including: a second sensor filter having a plurality of second cells divided by porous partition walls and collecting the particulate matter in the exhaust gas discharged from the filter; and at least one pair of second electrodes (32B, 33B) arranged to face each other with the second cell interposed therebetween so as to form a capacitor; and acquisition means, which are configured to acquire an efficiency of collecting the particulate matter in the filter, based on a first electrostatic capacitance between the pair of first electrodes and a second electrostatic capacitance between the pair of second electrodes, characterized in that the acquisition means are configured to acquire the first electrostatic capacitance and the second electrostatic capacitance at predetermined periods, to calculate a first electrostatic capacitance change rate from a plurality of first electrostatic capacitances including the latest first electrostatic capacitance, to calculate a second electrostatic capacitance change rate from a plurality of second electrostatic capacitances including the latest second electrostatic capacitance, and to acquire the efficiency of collecting the particulate matter in the filter based on the first electrostatic capacitance change rate and the second electrostatic capacitance change rate. a filter provided in an exhaust system of an internal combustion engine and collecting particulate matter in exhaust gas; a first sensor provided upstream of the filter in an exhaust direction of the exhaust gas and including: a first sensor filter having a plurality of first cells divided by porous partition walls and collecting the particulate matter in the exhaust gas to be introduced into the filter; and at least one pair of first electrodes (32A, 33A) arranged to face each other with the first cell interposed therebetween so as to form a capacitor; a second sensor provided downstream of the filter in the exhaust direction of the exhaust gas and including: a second sensor filter having a plurality of second cells divided by porous partition walls and collecting the particulate matter in the exhaust gas discharged from the filter; and at least one pair of second electrodes (32B, 33B) arranged to face each other with the second cell interposed therebetween so as to form a capacitor; and acquisition means, which are configured to acquire an efficiency of collecting the particulate matter in the filter, based on a first electrostatic capacitance between the pair of first electrodes and a second electrostatic capacitance between the pair of second electrodes, characterized in that the acquisition means are configured to acquire the first electrostatic capacitance and the second electrostatic capacitance at predetermined periods, to calculate a first electrostatic capacitance change rate from a plurality of first electrostatic capacitances including the latest first electrostatic capacitance, to calculate a second electrostatic capacitance change rate from a plurality of second electrostatic capacitances including the latest second electrostatic capacitance, and to acquire the efficiency of collecting the particulate matter in the filter based on the first electrostatic capacitance change rate and the second electrostatic capacitance change rate.