We investigated subjects about preferred whiteness on photo paper for inkjet printing. This investigation showed that the preferred whiteness score was high when subjects cannot sense the color or can sense a little blue color. Moreover, we divided subjects into two groups, one is the people who have used photo paper, and the other is the people who have not used it. From this investigation, we found the fact that the people who have used it is more sensitive the color on photo paper than the people who have not used. The fact suggests that experienced people have ideal whiteness in themselves. From now on, we need to investigate subjects who have more experience in using photo paper.