The most preferred luminance of Head Mounted Display (HMD) was investigated under two initial surround lights. It is found that though the initial preferred HMD luminance was affected by the surround lights, the preferred luminance of HMD is about 28 cd/m2 after 2 minutes regardless of the initial surround conditions. From the verification experiment using the complex images, it is confirmed that low luminance image is preferred than the original for 81% cases.