Cryptomeria japonica (Japanese cedar, JC) was prepared into veneers and mass–produced into laminated veneer lumber (LVL), and the residual cores from the rotary cutting of the log were employed as the test specimens and compared with that of Pinus radiate (Radiata pine, RP). The Aspergillus niger, Aspergillus flavus, and the Laetiporus sulphureus of brown–rot fungi, the Lenzites betulina of white–rot fungi were used to test the fungi and decay resistance. The residual cores were buried in the field, and the LVLs were placed in the outdoor corridor to evaluate the natural durability. The resistance to microbial deterioration of various specimens was investigated. The JC veneer had better fungi resistance than RP, with a significant difference between them. The perpendicular direction of JC LVL had a higher fungal growth rate than that of the RP, but there was no significant difference. According to the decay resistance results of white-rot fungi, there were insignificantly between the weight loss rate of JC veneer, parallel direction of JC LVL, and perpendicular direction of JC LVL, and those of RP. The weight loss rate of parallel direction and perpendicular direction of JC LVLs evaluated by brown–rot fungi was only half of the RP. After the burial test in the field of 18 months, the weight retention rate of the residual cores after the rotary cutting of log was 92.74%, whereas that of RP was 52.79% with its core specimens showing a biological deterioration appearance obviously. After the durability test of 36 weeks in the outdoor corridor, the weight loss rates of JC and RP LVLs were 4.11 and 8.31%, respectively. The JC LVL had a better resistance to microbial deterioration and natural durability than the RP.