Most　of　the　present　information　retrieval　systems　presuppose　subject　keywords　as　anaccess　point　as　well　as　the　criterion　for　relevance　judgment．　ln　other　words，　IR　systems　mainlydetermine　relevant　documents　by　keywords．　However，　users　may　look　at　other　documentcharacteristics　in　addition　to　the　subject　when　judging　relevance　of　the　documents．　This　meansthat　criteria　of　judging　relevance　between　the　system　and　end－users　may　be　different．　ln　orderto　overcome　the　discrepancy，　it　is　necessary　to　make　clear　what　kinds　of　non－keywordinformation　are　necessary　for　user’s　relevance　judgments　and　how　they　are　identified　and　usedfor　relevance　judgment．　　　Firstly　this　paper　investigated　whether　and　how　each　of　the　17　characteristics　thatdocuments　for　3　graduated　students　and　3　information　specialists．　usually　have　was　used　forthe　judgment　of　relevance　by　IR　users．　A　survey　was　conducted．　The　result　of　the　surveyshowed　that　users　judged　relevance　using　various　information　from　the　17　characteristics．Non－keyword　information　which　contains　events，　research　methods　and　novelty　of　the　idea，　aswell　as　the　length　of　original　documents　and　of　abstracts　were　determined　as　predominantinformation　for　judging　relevance．　Non－keyword　information　has　the　same　importance　as　theinformation　from　keywords　in　retrieving　documents．　　　Secondly，　the　author　discussed　the　applicability　of　those　kinds　of　information　to　enhanceretrieval　performance．　Such　kind　of　information　as　the　length　of　documents　and　publicationdates　will　be　easily　implemented　into　IR　systems　since　they　are　parts　of　bibliographic　data．Others　such　as　novelty　are　more　difiicult　to　use，　because　the　value　of　those　kinds　of　informationare　dependent　on　individual　user．Finally，　this　paper　suggests　the　possibility　to　introduce　user　models　into　a　IR　system　sinceuser　models　can　represent　such　characteristics　of　each　user　as　novelty．　They　will　be　helpful　forthe　system　to　deal　with　non－keyword　information．