A DPF target temperature setting unit has a temperature increase rate setting portion which sets a temperature increase change rate such that, until a target set temperature at which PM is burnt is reached after the start of late post injection, the temperature increase change rate is reduced in accordance with an increase in temperature or a period of time elapsed since the start of the late post injection, a stepwise temperature increase change rate in the temperature increase rate setting portion includes two stages of a first-stage change rate A and a second-stage change rate B lower than the first-stage change rate, and a target temperature of the DPF temperature is calculated by using the temperature increase rate of the temperature increase rate setting portion.