Using plant microfiber bundles with a nanometer unit web-like network, a moulded product with a bending strength of 250 MPa was obtained without the use of binders. High interactive forces seem to be developed between pulp fibers owing to their nanometer unit web-like network. In other words, the area of possible contact points per fiber are increased, so that more hydrogen bonds might be formed or van der Waals forces increased. When 2% oxidized tapioca starch, by weight, was added, the yield strain doubled and the bending strength reached 310 MPa. The starch mixed moulded product had a similar stress strain curve to that for magnesium alloy, and three to four times higher Young's modulus and bending strength values than polycarbonate and GFRP (chopped). The mouldings have a combination of environmentally friendly and high strength properties.