Exhaust gas purifying apparatus with post fuel injection quantity control

Provided is an exhaust gas purifying apparatus capable of making a filter entrance temperature reach a target temperature while suppressing excessive temperature increases and release of hydrocarbon even upon extension of the exhaust path length or decreases in outside air temperature. The exhaust gas purifying apparatus includes an oxidation catalyst (18) and a filter (19) that are placed in an exhaust path (5) of an engine (1), a fuel injection device (13) for injecting fuel in accordance with a fuel injection pattern, and a control device (50) configured to be capable of setting the fuel injection pattern including post-injection (QP), wherein an upper-limit value of post-injection quantity (QPbU, QPcU) increases with decreasing outside air temperature and/or with elongating path length of the exhaust path (5).