PURPOSE: To make it possible to obtain a welding rod for cast iron which contains specified percentages of C and Si, which has a specified CES value (%C+0.31% Si) and graphite structure having specified grain number of graphite, and which can make welding without requiring preheating, post heating, etc.

CONSTITUTION: The above-mentioned welding rod is nodular graphite cast iron made welding rod having a chemical composition of 3.1W4.5% C, 1.5W5.5% Si and 5W5.3 CES value (%C+0.31% Si), and a graphite structure composed of nodular graphite having ≥400 grains/mm2 graphite grains, and containing ≥0.1% C as a crystallized free cementite in the ground mass structure. This welding rod does not required preheating, post heating, etc., for making welding and even graphitizing annealing treatment can also be omitted for this welding rod.