To elucidate relationships between changes in brain activity associated with emotional image presentation, EEG spectra were analyzed in the resting state and during Positive or Negative image presentation using wearable electrical encephalogram (EEG) device and custom image presentation software developed in our laboratory. When alpha band power spectra were compared between resting state and emotional image presentation conditions, power spectrum values in the resting state were found to decrease in both positive and negative image presentation conditions. In particular, alpha band attenuation was strongly observed in negative image presentation conditions. These results suggest that a wearable EEG device may be able to detect changes in brain activity associated with visual information.