Plastic-worked lumber. PW1 and PW2 has air-dried specific gravity twice or more than those of lumber before processing NW1 and NW2 and acute crossing angles within a range of 45 degrees or less. The acute crossing angles are formed by all of annual ring lines RL on a butt end surface of the plastic-worked lumber PW1 or PW2 and a heart-side cross grain surface or a pith-side straight grain surface of the plastic-worked lumber PW1 or PW2. The plastic-worked lumber PW1 and PW2 is prepared by heating and compression to lumber NW1 or NW2 so that the lumber NW1 or NW2 is heated and compressed in a thickness direction thereof and plastically worked.