PURPOSE: To increase the rigidity of a member and decrease its weight, by glueing reinforcing layers of carbon fiber to both sides of a core part pasted together with a plurality of layers of woods, simultaneously with pasting putty of fiber reinforced plastics (FRP) contg. a microfoaming material further onto the both sides of said layer and then performing the work of coating finish with paint.

CONSTITUTION: To both sides of a core part pasted together with a plurality of layers of woods 1a, 1b, reinforcing layers 3 of carbon fiber are glued, while putty 4 of fiber reinforced plastic (FRP) contg. a microfoaming material is simultaneously pasted further onto the both sides of said layer and then the external surface is subjected to finishing work with urethane paint 5. Use of a composite material with wood of high compressive and fatigue strength for its core can obtain a boat member with high rigidity as well as light weight.