Oligoesterification of wood was investigated by alternately adding esterification reactions of wood with maleic anhydride and allyl glycidyl ether. The products obtained consisted of acetone-insoluble and soluble parts. The insoluble parts were novel oligoesterified woods with oligoester chains having polymerizable double bonds. The oligoester chain length showed a tendency to decrease with increase in wood content in feed. The soluble parts were free oligoesters which were not linked with the wood matrix. The products (the oligoesterified wood-containing mixtures), when subjected to hot-pressing in the presence of a peroxide, gave plasticized crosslinked wood boards whose surfaces are smooth, glossy, and plasticlike. In this case, the free oligoesters which were hardening worked as a plasticizer for the wood components and were combined, by the crosslinking, with the oligoesterified woods, resulting in the formation of the network structure. The crosslinked wood boards exhibited outstanding properties in heat distortion temperature (>165°C) and compressive strength (ca. 1,600–2,300 kg/cm2).