Provided is a construction machine that can prevent lowering of a vehicle because a blade is not placed in a floating state even when an operator has performed an erroneous operation if the vehicle isin a jacked-up state and that can place the blade in a floating state and perform satisfactory leveling work in accordance with the operator operation if the vehicle is not in a jacked-up state. A hydraulic shovel comprises a controller (42) that determines whether the vehicle is in a jacked-up state and that controls a float valve (41). When the vehicle is determined not to be in a jacked-up state, the controller (42), in accordance with a float command, switches the float valve (41) to a float position (V) and disables operation of a blade control valve (22). When the vehicle is determinedto be in a jacked-up state, the controller (42), regardless of the existence of a float command, maintains the float valve (41) in a standard position (IV) and enables operation of the blade control valve (22).