A component mounter comprising: a component supply device configured to sequentially supply components (80, 81, 82) to be mounted on a board; an imaging device (14, 15); and a first determination section configured to execute a supply state determination by imaging the component by using the imaging device (14, 15) before the component (80, 81, 82) is picked up at a picking up position; characterized in that the first determination section is configured to determine whether a supply state of the component (80, 81, 82) in the component supply device is appropriate for first components which are a predetermined number of the components (80, 81, 82) smaller than the number of the components (80, 81, 82) supplied from the component supply device to the board, wherein the first determination section determines that the supply state of the first component is appropriate when both a position and an angle of the first component, when the first component is positioned at an imaging position, are included in a predetermined range; and the component mounter comprises a second determination section configured to determine (S13, S14) necessity of the supply state determination for a second component which is the component (80, 81, 82) supplied from the component supply device after the first component is supplied, based on a result of determination by the first determination section; and a timing setting section configured to set (S15, S16) an operation start timing (TG1, TG2), at which a holding member, picking up and hold the component to mount the component (80, 81, 82) on the board, starts a lowering operation for picking up the component (80, 81, 82), for both of the first component and the second component, wherein an imaging position of the component (80, 81, 82) when the component (80, 81, 82) is imaged, and the picking up position of the component (80, 81, 82) when the component (80, 81, 82) is picked up coincide with each other, and when the operation start timing at which the lowering operation of the holding member is started after the component (80, 81, 82) is positioned at the picking up position is defined as a first timing, and the operation start timing which is set earlier than at least the first timing by a required time from when the holding member starts the lowering operation to when the holding member reaches the component (80, 81, 82) is defined as a second timing, the second determination section is configured to determine that the supply state determination is not required for the second component, when it is determined that a supply state of the first component is appropriate by the first determination section, and the timing setting section is configured to set the first timing for the first component and sets the second timing for the second component. a component supply device configured to sequentially supply components (80, 81, 82) to be mounted on a board; an imaging device (14, 15); and a first determination section configured to execute a supply state determination by imaging the component by using the imaging device (14, 15) before the component (80, 81, 82) is picked up at a picking up position; characterized in that the first determination section is configured to determine whether a supply state of the component (80, 81, 82) in the component supply device is appropriate for first components which are a predetermined number of the components (80, 81, 82) smaller than the number of the components (80, 81, 82) supplied from the component supply device to the board, wherein the first determination section determines that the supply state of the first component is appropriate when both a position and an angle of the first component, when the first component is positioned at an imaging position, are included in a predetermined range; and the component mounter comprises a second determination section configured to determine (S13, S14) necessity of the supply state determination for a second component which is the component (80, 81, 82) supplied from the component supply device after the first component is supplied, based on a result of determination by the first determination section; and a timing setting section configured to set (S15, S16) an operation start timing (TG1, TG2), at which a holding member, picking up and hold the component to mount the component (80, 81, 82) on the board, starts a lowering operation for picking up the component (80, 81, 82), for both of the first component and the second component, wherein an imaging position of the component (80, 81, 82) when the component (80, 81, 82) is imaged, and the picking up position of the component (80, 81, 82) when the component (80, 81, 82) is picked up coincide with each other, and when the operation start timing at which the lowering operation of the holding member is started after the component (80, 81, 82) is positioned at the picking up position is defined as a first timing, and the operation start timing which is set earlier than at least the first timing by a required time from when the holding member starts the lowering operation to when the holding member reaches the component (80, 81, 82) is defined as a second timing, the second determination section is configured to determine that the supply state determination is not required for the second component, when it is determined that a supply state of the first component is appropriate by the first determination section, and the timing setting section is configured to set the first timing for the first component and sets the second timing for the second component.