A system includes a measured value storing device in which a product measured value acquired periodically and a manufacturing condition measured value are stored, a product threshold value setting device that sets a product threshold value for determining whether a product is normal or not, an abnormality accumulating device that acquires a product abnormality cumulative frequency where the product abnormality measured value exceeds the product threshold value, a product threshold value changing device that changes the product threshold value, a condition threshold value setting device that sets a condition threshold value to be compared with a manufacturing condition measured value, a condition abnormality accumulating device that acquires a condition cumulative frequency, a condition threshold value changing device that changes a condition threshold value, and a cause identifying device that identifies a cause of abnormality based on the distribution of the product abnormality cumulative frequency and a manufacturing condition cumulative frequency.