A synesthetic metaphor (e.g., "sweet touch") is a metaphor that results from a combination of a modifier and a head, where they express different perceptual qualities. Most of the existing studies examine how the acceptability of synesthetic metaphors can be explained by the pairing of adjective modifiers and head nouns modalities. However, little attention has been paid to how people comprehend synesthetic metaphors. This paper explores how people comprehend Japanese synesthetic metaphors. In our psychological experiment we collected 10388 words associated with 62 synesthetic metaphors and classified them into the following four kinds of features: common (features listed for the metaphor, the vehicle and the topic), vehicle-shared (features listed for both the metaphor and the vehicle, but not listed for the topic), topic-shared (features listed for both the metaphor and the topic, but not listed for the vehicle), and emergent (features listed for the metaphor, but not listed for either the vehicle or the topic). The result showed that there were significantly more emergent features than the other kinds of features in the comprehension of synesthetic metaphors. This result suggests that we do not so directly comprehend synesthetic metaphors based on salient features of the vehicle or the topic. In this paper we focus on event knowledge which is assumed to play a crucial role in comprehending synesthetic metaphors. We analyzed how many words associated with synesthetic metaphors could be classified into those based on event knowledge. The results showed that there were significantly more words based on event knowledge than those which could not be classified as words based on event knowledge. This result suggests that event knowledge play an important role in comprehending synesthetic metaphors.