The present study tried to detect semantic distances by Event-related Potentials (ERPs) The semantic distances of product images were classified into four dimensions- affectivity, novelty, modernity, and complexity by using mean, standard deviation, skewness, and kurtosis. In ERP test, the picture-word matches of various semantic distances in terms of congruence, ambiguity, and incongruence were used as stimuli for detecting N400 effects. The results showed that the reaction times of congruence were faster than those of incongruence. The reaction times of the congruence were the same as those of ambiguity. These findings suggested that the features of images with conformity context for the words could decrease the participants’ speed of identification. On the contrary, the differential features of images for the words could increase participants’ reaction times. Moreover, the shorter reaction time was noted to congruent stimuli, while ambiguous and congruent stimuli triggered equally fast responses. The incongruent combination elicited N400 responses in right posterior cerebrum; the ambiguous combination triggered only slightly N400 responses in left posterior cerebrum, while the congruent combination did not demonstrate N400 effects. The mechanism of N400 effects to the incongruent combinations is mainly denial to the stimuli in the context, while bilateral confirmation is involved in the reactions to the ambiguous combinations. Therefore, ERP may be applied in the future as an auxiliary tool to measure the semantic ambiguity in product design.