A welding state monitoring device capable of monitoring a welding state by a n image obtained by photographing a working portion under welding by an image sensor, comprising a means for taking out an intensified output from the ima ge sensor in any brightness area by using a conversion table for the output characteristics of the image sensor, whereby a welding portion and a bead portion in glaring light of welding can be clearly observed with a sufficien t contrast from the image photographed with a wide dynamic range covering an area ranging from a high bright area (Kb) at the welding portion under weldi ng to a low bright area (Ka) at the bead portion.
