Wooden　components　were　removed　from　ancient　buildings　and　used　as　experimental　materials.　The　drilling　curve　and　feed　curve　were　generated　from　data　collected　by　a　resistograph,　and　the　wood　density　was　predicted　by　using　the　information　diffusion　model.　A　significant　correlation　was　observed　between　the　data　for　micro-drilling　resistance　and　wood　density.　The　information　diffusion　methodology　was　able　to　predict　the　wood　density　by　the　nonlinear　method　very　well.　Using　the　two-curve　effect　weight,　when　the　drilling　curve　data　and　the　feed　curve　data　were　0.2　and　0.8,　respectively,　the　error　was　minimum,　with　an　average　relative　error　of　3.82%.　Therefore,　the　data　supported　on-site　ancient　building　repair　work.