A component mounting system that includes a component mounter in which multiple component supply units that supply components are detachably arranged, the system comprising: a unit exchange device configured to automatically exchange a component supply unit between the unit exchange device and the component mounter ; an instruction output section configured to output an instruction list to an operator, the instruction list including exchange instruction of the component supply units , including an automatic exchange instruction to the unit exchange device , wherein, in the instruction list: - attachment and detachment instructions are registered, and - a type of attachment and detachment, indicating the attachment or the detachment, is associated with identification information identifying the component supply unit targeted to be attached and detached, and positional information for the attachment and detachment in the component mounter ; an acquisition section configured to acquire an attachment and detachment record that includes the identification information on the component supply unit , the positional information on the attachment and detachment, and the type of attachment and detachment when the component supply unit is attached and detached on the component mounter ; and a processing section configured to determine whether the attachment and detachment of the component supply unit is performed according to the attachment and detachment instruction based on the attachment and detachment record acquired by the acquisition section and the instruction list, and when it is determined that the attachment and detachment is performed according to the attachment and detachment instruction, perform an update process to update the instruction list by deleting the corresponding attachment and detachment instruction. a unit exchange device configured to automatically exchange a component supply unit between the unit exchange device and the component mounter ; an instruction output section configured to output an instruction list to an operator, the instruction list including exchange instruction of the component supply units , including an automatic exchange instruction to the unit exchange device , wherein, in the instruction list: - attachment and detachment instructions are registered, and - a type of attachment and detachment, indicating the attachment or the detachment, is associated with identification information identifying the component supply unit targeted to be attached and detached, and positional information for the attachment and detachment in the component mounter ; - attachment and detachment instructions are registered, and - a type of attachment and detachment, indicating the attachment or the detachment, is associated with identification information identifying the component supply unit targeted to be attached and detached, and positional information for the attachment and detachment in the component mounter ; an acquisition section configured to acquire an attachment and detachment record that includes the identification information on the component supply unit , the positional information on the attachment and detachment, and the type of attachment and detachment when the component supply unit is attached and detached on the component mounter ; and a processing section configured to determine whether the attachment and detachment of the component supply unit is performed according to the attachment and detachment instruction based on the attachment and detachment record acquired by the acquisition section and the instruction list, and when it is determined that the attachment and detachment is performed according to the attachment and detachment instruction, perform an update process to update the instruction list by deleting the corresponding attachment and detachment instruction. <EOS>