An exhaust gas cleaning device estimates a deposition amount of exhaust particulate matters in a collector based on deposition characteristics correlating the deposition amount with a pressure loss at the collector. The deposition characteristics define a first range from an initial point, at which the deposition amount is zero, to a transitional point and a second range over the transitional point. The pressure loss increases more gradually in the second range than in the first range as the deposition amount increases. The exhaust gas cleaning device corrects the deposition characteristics such that the transitional point approaches the initial point, the pressure loss at the initial point increases and an increase ratio of the pressure loss to the increase of the deposition amount in the second range increases as an ash deposition amount increases.