TiAl intermetallic compound was candidated for the application to the high temperature materials such as a gas turbine exhaust valve in the automobile. However, this material dose not have ductility allowing to machinability to product. To improve the ductility, many researches conduct alloy design and heat treatment methods. We observed that the microstructure of TiAl varied with Ni, Mn elements as well as a heat treatment condition. In the case of Ni element addition, the TiAlNi intermetallic compound was precipitated at the grain boundary. When the heat treatment temperature increased from 1000℃ to 1300℃, the TiAlNi intermetallic compound was uniformly dispersed on the matrix. In the case of Mn element addition, the mixed duplex structure of γ-TiAl and lamellar(TiAl/Ti₃Al) was obtained with 1250℃ and 1300℃ heat treatment for 1hour. When the heat treatment temperature increased from 1250℃ to 1300℃, the lamellar domain of the duplex structure was transformed near-lamellar structure.