In this study, we examine the economic incentive to select political bias of news on Internet portals. The news slant is measured based on the expressions in congressional speeches in 2015, following Gentzkow and Shapiro (2010). The whole articles posted on two major domestic portals in the same year are used for the analysis. The higher the index value, the stronger the slant toward the ruling party. As a result, both portals locate somewhat farther from the ideology of the ruling party. Also, as the difference between portal and user increases, the number of clicks on news page decreased. The slant of portal was positively correlated with consumer 's political preference. In other words, consumers try to click on more news close to one’s preference, and the portal seems to select the news contents accordingly. We can interpret this as a profit maximization strategy of the portals in the online advertising market. In addition, there is a differentiation effect between the two portals regarding the news slant, but the size is small. These results suggest that a further discussion on the relevance and effectiveness of self-regulation in the portal news industry is necessary.