Electricity wasting due to an unnecessary operation is prevented and the usability is improved. A multi air conditioner includes an outdoor unit, a first indoor unit and a second indoor unit. The first indoor unit and the second indoor unit are connected to the outdoor unit and are respectively disposed in different rooms. When the first indoor unit is operated based on a first operating mode, if an operation start instruction based on a second operating mode which is different from the first operating mode is sent to the second indoor unit from a remote controller without using an internet (S5: YES, S7: NO), the first indoor unit becomes an operation stop state and the second indoor unit starts an operation based on the second operating mode on condition that the last instruction to the first indoor unit is sent from a smart phone via the internet (S9: YES) (S12).