A component-mounting block of an electronic component-mounting apparatus has mounting heads installed thereon. Each mounting head has a nozzle-replacing device for replacing at least one selected sucking nozzle by at least one other sucking nozzle to be newly selected. The replacement is possible during travel of the component-mounting block between a mounting position and a sucking position effected by a X-Y moving stage. At least one mounting head carries at least one sucking nozzle rotatable about a vertical axis of a nozzle holder. The mounting head has the nozzle holder, and an engaging member holder. Sucking nozzles are circumferentially arranged about the vertical axis of the nozzle holder and vertically retractably held by the nozzle holder. The engaging member holder holds engaging members which engageably face the nozzles. The nozzles are engaged with the engaging members when the holders are relatively vertically moved toward each other, and are retracted when the holders are moved away from each other. The engagement can be prevented. A selected engaging member is prevented from engaging with a corresponding sucking nozzle by rotating the holders about the vertical axis. Alternatively, at least one nozzle is disengaged from a corresponding engaging member at a desired rotational angle of the holders.