Provided is a method for identifying and suppressing abnormal growth of fibroblasts at an early stage. Provided is a method for identifying the growth state of fibroblasts using as an index the level of expression of ETFB (electron transfer flavoprotein beta subunit), comprising: judging, in cases where the level of expression of ETFB is high, that there is a high probability that fibroblasts are abnormally growing； and judging, in cases where the level of expression of ETFB is low, that there is a high probability that fibroblasts are normally growing. Further, by inhibition of ETFB, abnormal growth of fibroblasts can be suppressed.
