|This study examines how ownership concentration affects technology innovation activity (TIA) of Korean firms listed in KOSPI and KOSDAQ markets. Our principal findings are as follows. First, the ownership concentration has a positive effect on TIA. Both business age and leverage affect negatively on TIA, while growth opportunity does positively. Second, a quantile regression analysis shows that the effect of ownership concentration is stronger at higher quantiles of R&D expenditures. Third, ownership concentration presents a greater impact on TIA for venture·innobiz firms than for non-venture.innobiz ones. Fourth, we find that the coefficient of ownership concentration is much higher for high R&D expenditure group than low R&D expenditure group. TIA is intrinsically a risky project in which its performance is realized in a long term. Thus, firms with dispersed ownership have great difficulties when one executes TIA with a high risk. In a nutshell, it may be said that ownership concentration significantly contributes to an increase in TIA of Korean listed firms. This effect of ownership concentration on TIA is stronger in high R&D expenditure firms.