Abstract: The present invention provides high quality laminated veneer lumber as a material for such uses as in architecture and furniture, and a method of mass production thereof using veneer which is flattened in advance. A sheet of veneer is obtained by cutting a log with a rotary lathe or the like, and flattening and cutting the same into a predetermined length. Sheets of veneer thus obtained are cut on both edges in the grain direction to form symmetrically diagonal end faces and bonded with one another at said end faces with their grain directions aligned to form an elongated sheet of veneer. The resultant elongated sheet of veneer is cut into a predetermined length to form a laminated veneer material having seams a. Plural sheets of thus formed laminated veneer material are laminated and bonded with their grain directions aligned to form laminated veneer core 3. The laminated veneer core 3 is either directly used as a laminated veneer lumber, or is covered with another sheet of seamless veneer 4 on its surface.