Disclosed is a welding structural steel product having TiN and Zrn precipitates, which contains, in terms of percent by weight, 0.03 to 0.17 % C, 0.01 to 0.5 % Si, 0.4 to 2.0 % Mn, 0.005 to 0.2 % Ti, 0.0005 to 0.1 % A1, 0.001 to 0.03 % Zr, 0.008 to 0.030 % N,0.0003 to 0.01 % B, 0.001 to 0.2 % W, at most 0.03 % P, 0.003 to 0.05 % B S, at most 0.01 O, and balance Fe and incidental impurities while satisfying conditions of 1.2 </= Ti/N </= 2.5, 0.3 </= Zr/N </= 2.0, 10 </= N /B </= 40, 2.5 </= A1/N </= 7, and 6.8 </= (Ti+Zr+2A1+4B) / N </= 17, and having a microstructure essentially consisting of a complex structure of ferrite and pearlite having a grain size of 20 mu m or less. |