A component mounting system, comprising: a component supply section (28, 81) configured to supply a component to be mounted at a predetermined position of a board; a pickup nozzle (26, 62) configured to pick up the component supplied by the component supply section (28, 81); an imaging section configured to capture an image of the component picked up by the pickup nozzle (26, 62) and acquire image data; a memory section configured to store image data captured by the imaging section; an image processing execution section configured to perform image processing on the image data captured by the imaging section; a determining section (100, 102) configured to determine acceptability of the component and a position of the component based on the image data subjected to the image processing by the image processing execution section; an error rate calculating section (100, 102) configured to calculate an error rate that is a ratio of determination results indicating an unacceptable result among a predetermined number of determination results from determination results obtained by the determining section (100, 102) for a predetermined number of images; a storage period monitoring section (100, 102) configured to start a storage period, during which the image data is stored in the memory section, when the error rate calculated by the error rate calculating section (100, 102) is larger than a predetermined reference error rate, and to end the storage period when the error rate calculated by the error rate calculating section (100, 102) is less than or equal to the reference error rate, and a storage control section (100, 102) configured to store the image data captured by the imaging section in the memory section during the storage period, characterized by: a reference setting section connected to the storage period monitoring section (100, 102) capable of setting the reference error rate for each of multiple components mounted on the board. a component supply section (28, 81) configured to supply a component to be mounted at a predetermined position of a board; a pickup nozzle (26, 62) configured to pick up the component supplied by the component supply section (28, 81); an imaging section configured to capture an image of the component picked up by the pickup nozzle (26, 62) and acquire image data; a memory section configured to store image data captured by the imaging section; an image processing execution section configured to perform image processing on the image data captured by the imaging section; a determining section (100, 102) configured to determine acceptability of the component and a position of the component based on the image data subjected to the image processing by the image processing execution section; an error rate calculating section (100, 102) configured to calculate an error rate that is a ratio of determination results indicating an unacceptable result among a predetermined number of determination results from determination results obtained by the determining section (100, 102) for a predetermined number of images; a storage period monitoring section (100, 102) configured to start a storage period, during which the image data is stored in the memory section, when the error rate calculated by the error rate calculating section (100, 102) is larger than a predetermined reference error rate, and to end the storage period when the error rate calculated by the error rate calculating section (100, 102) is less than or equal to the reference error rate, and a storage control section (100, 102) configured to store the image data captured by the imaging section in the memory section during the storage period, characterized by: a reference setting section connected to the storage period monitoring section (100, 102) capable of setting the reference error rate for each of multiple components mounted on the board.