In recent years, measurement techniques and devices of cerebral function and brain activity have been improved. Therefore, "Neuromarketing" has been attracting attention. Neuromarketing is one of commercial activities and is in the marketing researches which study comsumers' response to purchase activity. Neuromarketing is helpful for companies to elucidate principles of actions unconsciously caused by human and has 2 purposes to increase effectively consumers' eagerness to buy. First purpose is elucidating what consumers bought for indexes at the time of purchasing decision making. Second purpose is elucidating what consumers regard as important in the indexes. fMRI is used mainly for such a brain activity measurement. However, there are several problems to use fMRI, which has limitation on the posture of the subject is very expensive. Therefore, it is expected that a portable NIRS (Near-infrared spectroscopy) brain measuring apparatus may be suitable for a study of neuromarketing. We investigate the relation between impressions of the product brand and consumers' brain response. From our investigation, we show that different brand impression results in different effect on the cerebral blood flow by a portable NIRS brain measuring apparatus.