A mounting processing method performed at a component mounter, comprising: using the component mounter to perform mounting processing of mounting multiple types of components on a board, the multiple types of components being supplied from multiple component supply units configured to house multiple components and be exchangeably set by a unit exchanging device, wherein during mounting processing of one of the boards, from the multiple component supply units set on the component mounter, a component supply unit with remaining housed components is exchanged with a different component supply unit by the unit exchanging device, the mounting processing method further including starting mounting processing in a state in which, from the multiple component supply units required for mounting processing, a portion of the multiple component supply units are set on the component mounter and a remaining portion of the component supply units are not set on the component mounter, and during mounting processing of one of the boards, performing mounting processing while exchanging the component supply unit that has completed supplying the components during the mounting processing from among the portion of component supply units set on the component mounter with one of the component supply units of the remaining portion, and performing mounting processing by using a head to pick up the component supplied by the component supply unit and then moving the head above the board via a specified position, characterized in that during the mounting processing, from among the component supply units that have completed supplying the components, taking as a target for exchange the component supply unit set at a position for which a moving distance for the head from picking up the component to moving to the specified position is shorter than the one for another component supply unit, and using the unit exchanging device to perform exchange of the target component supply unit with one of the component supply units of the remaining portion. using the component mounter to perform mounting processing of mounting multiple types of components on a board, the multiple types of components being supplied from multiple component supply units configured to house multiple components and be exchangeably set by a unit exchanging device, wherein during mounting processing of one of the boards, from the multiple component supply units set on the component mounter, a component supply unit with remaining housed components is exchanged with a different component supply unit by the unit exchanging device, the mounting processing method further including starting mounting processing in a state in which, from the multiple component supply units required for mounting processing, a portion of the multiple component supply units are set on the component mounter and a remaining portion of the component supply units are not set on the component mounter, and during mounting processing of one of the boards, performing mounting processing while exchanging the component supply unit that has completed supplying the components during the mounting processing from among the portion of component supply units set on the component mounter with one of the component supply units of the remaining portion, and performing mounting processing by using a head to pick up the component supplied by the component supply unit and then moving the head above the board via a specified position, characterized in that during the mounting processing, from among the component supply units that have completed supplying the components, taking as a target for exchange the component supply unit set at a position for which a moving distance for the head from picking up the component to moving to the specified position is shorter than the one for another component supply unit, and using the unit exchanging device to perform exchange of the target component supply unit with one of the component supply units of the remaining portion.