Abstract: An apparatus for measuring the mass of particulates is disclosed. A low-temperature filter which is held at a temperature lower than the boiling point of the particulate liquid component contained in gas, and a high-temperature filter, which is held at a temperature higher than the boiling point of the liquid component but lower than the ignition point of the solid component of the particulates, are oscillated while they are contacted by a sample gas at the same rate. The mass of all particulates deposited on the low-temperature filter and the mass of the particulate solid component deposited on the high-temperature filter are calculated from each inherent oscillation frequencies of the two filters, while the mass of the liquid component is obtained by subtracting the mass of the solid component from the mass of the total particulates.