Free piston Stirling engines with integrated linear alternators have the compact size and high conversion efficiency for the sake of the simplicity of mechanical movements. These engines have been developed with the conversion efficiency of 25 %. The material property of ceramics heater is critical in order to achieve such high efficiency. In this paper, the successful design process of the ceramics heater is described. Temperature and stress of the ceramic heater have been calculated by the method of thermo-fluid dynamical analysis and the proper dimensions were decided. Several types of test products have also been designed and manufactured for the evaluation of actual efficiency. Heater efficiency of 63% was estimated from the analysis and the actual test data on free piston engine. It was concluded that the use of ceramics heater in Stirling engine is promising and the high performance of the engine can be realized.