Most infections occur on the leaves, causing diamond-shaped lesions with a grey or white center to appear, or on the panicles, which turn white and die before being filled with grain [3–5]. Breeding of disease-resistant varieties has been the most effective and economic way to control this disease but the resistance is often lost in a few years after cultivars released because of the high variability of the rice blast fungus. To breed rice varieties with more durable blast resistance, multiple resistance genes utilizing both qualitative and quantitative genes must be incorporated into individual varieties [1,6]. In contrast, traditional selections based on phenotypic screening need much more time. Thus, crop improvement in the disease resistance of rice requires new biotechnological tools. Recent advancements in the crop improvement using classical induction mutagenesis have been well established with many newly developed promising varieties created worldwide using both physical and chemical mutagens. Since the disease stresses have lowered rice productivity in Thailand, breeding of disease resistant genotypes using mutation induction assisting improvement in rice has been carried out. Many types of physical mutagenic sources, for example, X-ray, gamma-ray, ultra-violet light irradiation, neutron, and ion beam, have been developed and applied to crop mutation. In application of ion