In this study, I examine the relation between earnings quality and commonality of information contained in individual analysts' earnings forecasts after mandatory IFRS adoption in Korea. I also examine if this relation affects on analysts' forecast accuracy. Using the empirical proxies suggested by the Barron et al.(1998) model that is based on the acrossanalyst correlation in forecast errors, I conclude that after mandatory IFRS adoption the commonality of information among active analysts decreases, in other words, the idiosyncratic information contained in these individual analysts' forecasts increases. However, I find after mandatory IFRS adoption the commonality of information among active analysts increases as earnings quality is high. I also show that, as earnings quality is high, analysts' reliance on common information contributes to increase analysts' forecast accuracy after mandatory IFRS adoption. On the other hand, low earnings quality motivates analysts to work harder to develop or acquire relatively more idiosyncratic information in an effort to increase analysts' forecast accuracy. My results have implication for analysts seeking more idiosyncratic information in response to investors' demands after mandatory IFRS adoption. My results show that these analysts' behavior does help to increase analysts' forecast accuracy when earnings quality is relatively high. Therefore, it is important for analysts to consider earnings quality before they try to develop or acquire idiosyncratic information after mandatory IFRS adoption. When earnings quality is high it is enough for analysts to rely on only common information to increase the analysts' forecast accuracy. Low earnings quality, however, drives analysts work harder to gather idiosyncratic information to increase the accuracy.