This experiment was conducted to determine the effect of inorganic and organic sources and levels of magnesium (Mg) supplementation on plasma, tibia, meat and liver Mg concentration and mechanical properties of bones in broilers. A total of one day old 450 broiler chicks were used and assigned to six experiment groups each having five replicate, randomly. There were 15 chicks in each replicates. In the experiment magnesium sulphate (MgSO4) was used as inorganic Mg source and magnesium proteinate was used as organic Mg source. Experimental diets were supplemented provide 0 (control), 0.2 and 0.4 % Mg levels inorganic and organic Mg source of basal ration, and experiment period was six weeks. Main effect of Mg source and source x level interaction effect had not significant on plasma, liver, breast and thigh meat Mg concentration. While treatments did not significant effect on liver, breast and thigh meat Mg concentration, the main effect of Mg levels was significant effect on plasma Mg concentration. Plasma Mg concentration which were fed with ration added 0.2 and 0.4 % Mg level was higher than the control group. Tibia Ca concentration which were fed with ration added organic*0.2 and 0.4 % Mg levels were higher than the other groups. Tibia P concentration of organic Mg source fed with the group were higher than the inorganic source. The highest tibia Mg concentration were found to fed with organic*0.4 % Mg level of group. Tibia shear force and tibia stress which were fed with ration added 0.2 and 0.4 % Mg levels were higher than the control group. Supplementation of Mg in broiler diet was increased plasma Mg concentration and tibia shear force and also, tibia Ca and P concentration of organic Mg source fed with the group were higher than the inorganic Mg source.