Bayesian　updating　is　widely　applied　to　evaluate　the　failure　probability　of　a　deteriorating　structure;　however,　it　requires　considerable　computational　effort.　This　is　because　reliability　analysis　based　on　posterior　distributions　must　be　repeated　each　time　the　inspection　data　are　updated.　To　overcome　this　problem,　this　study　proposes　an　efficient　method　to　directly　update　the　failure　probability　of　a　deteriorating　structure.　In　the　proposed　method,　an　updating　factor　is　proposed　to　quantify　the　updated　information　by　separating　the　components　to　be　updated　from　the　reliability　analysis　with　the　direct　prior　distribution.　Thus,　both　the　need　to　repeat　the　structural　reliability　analysis　and　reacquire　posterior　distributions/samples　each　time　the　inspection　data　are　updated　can　be　avoided.　The　point-estimate　method　combined　with　the　bivariate　dimension-reduction　method　is　introduced　to　directly　update　the　failure　probability,　from　which　only　the　updating　factor　at　the　fixed　estimation　points,　that　is,　the　components　that　have　no　relationship　with　the　structural　analysis,　needs　to　be　updated,　thus　considerably　reducing　the　computation　time.　The　efficacy　and　accuracy　of　the　proposed　method　were　verified　through　four　numerical　examples,　wherein　commonly　used　methods　were　employed　for　comparison.