Fe—Cr alloy having excellent weldability and initial rust resistance with no requirement of greatly increasing the amount of elements such as Ni, Cu, Cr or Mo, addition of Nb or Ti and, further, excess reduction of C and N, in which the Fe—Cr alloy containing Cr in an amount of more than about 8.0 mass % and less than about 15 mass % is controlled specifically for the ingredients to contain Co: from about 0.01 mass % to about 0.5 mass %, V: from about 0.01 mass % to about 0.5 mass % and W: from about 0.001 mass % to about 0.05 mass %, and a value X represented by the following equation (1) and, preferably, a value Z represented by the following equation (2) satisfy: X≦11.0, and 0.03≦Z≦1.5 respectively: X value=Cr(mass %)+Mo(mass %)+1.5Si(mass %)+0.5Nb(mass %)+0.2V(mass %)+0.3W(mass %)+8Al(mass %)−Ni(mass %)−0.6Co(mass %)−0.5Mn(mass %)−30C(mass %)−30N(mass %)−0.5Cu(mass %)  (1) Z value=(Co(mass %)+1.5V(mass %)+4.8W(mass %))  (2) ,and more preferably, C/N is controlled to be 0.6 or less.