A construction machine comprising: an electrical equipment installed in a vehicle body ; a urea SCR controller installed in the vehicle body ; and a battery configured to supply power to the electrical equipment and the urea SCR controller , wherein the construction machine further comprises: a plus-side main connection line configured to connect the electrical equipment and a plus terminal of the battery ; a plus-side isolating switch provided on the plus-side main connection line configured to connect or disconnect the electrical equipment to or from the plus terminal of the battery ; a key switch positioned at a downstream side of the plus-side isolating switch and is connected in series to the plus-side isolating switch , configured to connect or disconnect the electrical equipment to or from the plus terminal of the battery ; a plus-side auxiliary connection line positioned at an upstream side of the plus-side isolating switch configured to connect the urea SCR controller and the plus terminal of the battery ; a minus-side main connection line configured to connect a minus terminal of the battery to ground; and a minus-side isolating switch provided on the minus-side main connection line configured to connect or disconnect the minus terminal of the battery to or from ground. an electrical equipment installed in a vehicle body ; a urea SCR controller installed in the vehicle body ; and a battery configured to supply power to the electrical equipment and the urea SCR controller , wherein the construction machine further comprises: a plus-side main connection line configured to connect the electrical equipment and a plus terminal of the battery ; a plus-side isolating switch provided on the plus-side main connection line configured to connect or disconnect the electrical equipment to or from the plus terminal of the battery ; a key switch positioned at a downstream side of the plus-side isolating switch and is connected in series to the plus-side isolating switch , configured to connect or disconnect the electrical equipment to or from the plus terminal of the battery ; a plus-side auxiliary connection line positioned at an upstream side of the plus-side isolating switch configured to connect the urea SCR controller and the plus terminal of the battery ; a minus-side main connection line configured to connect a minus terminal of the battery to ground; and a minus-side isolating switch provided on the minus-side main connection line configured to connect or disconnect the minus terminal of the battery to or from ground. a plus-side main connection line configured to connect the electrical equipment and a plus terminal of the battery ; a plus-side isolating switch provided on the plus-side main connection line configured to connect or disconnect the electrical equipment to or from the plus terminal of the battery ; a key switch positioned at a downstream side of the plus-side isolating switch and is connected in series to the plus-side isolating switch , configured to connect or disconnect the electrical equipment to or from the plus terminal of the battery ; a plus-side auxiliary connection line positioned at an upstream side of the plus-side isolating switch configured to connect the urea SCR controller and the plus terminal of the battery ; a minus-side main connection line configured to connect a minus terminal of the battery to ground; and a minus-side isolating switch provided on the minus-side main connection line configured to connect or disconnect the minus terminal of the battery to or from ground. <EOS>