toughness the al amount is preferably not more than 0 012 the sulfur amount should be a lower level because sulfur forms inclusion mns to deteriorate the material in toughness the sulfur amount is preferably not more than 0 015 the amounts of p sn sb as and so on should be lower because these elements are liable to generate temper embrittlement of the material preferably the p amount is not more than 0 020 the sn amount is not more than 0 015 the sb amount is not more than 0 004 and the as amount is not more than 0 015 the invention low alloy steel material for generator rotor shafts may be produced by the following process 1 a melt of the material prepared by means of an electric furnace and thereafter the melt is refined by a vacuum degassing process a carbon deoxidation process under vacuum or an electroslag remelting process 2 the thus produced melt is cast into a die to produce an ingot 3 the ingot is subjected to hot forging at a temperature of not lower than 1150 u00b0 c subsequent normalizing at a temperature of not lower than 840 u00b0 c and subsequent tempering at a temperature of not lower than 600 u00b0 c to.