Steel for manufacturing cemented steel parts, characterized in that the composition thereof in weight percentages is: 0.1%≦C≦0.15%; 0.8%≦Mn≦2%; 1%≦Cr≦2.5; 0.2%≦Mo≦0.6%; trace elements≦Si≦0.35%; trace elements≦Ni≦0.7%; trace elements≦B≦0.005%; trace elements≦Ti≦0.1%; trace elements≦N≦0.01% if 0.0005%(5ppm)≦B≦0.005%, and trace elements≦N≦0.02% if trace elements≦B≦0.0005%(5ppm); trace elements≦Al≦0.1%; trace elements≦V≦0.3%; trace elements≦P≦0.025%; trace elements≦Cu≦1%, preferably≦0.6%; trace elements≦S≦0.1%; the remainder being iron and impurities resulting from production. A cemented steel part made with this steel, and to the method for manufacturing same.