Design and Implementation of Retargetable Software Debugger Based on GDB Many processors for embedded system have been developed and is widely being used in many industrial area. If we develop a new embedded processor, we need a simulator, compiler, and debugger for developing an operating system and basic program running on the embedded processor. The debugger is used for finding the error in a program. theses software are very important in embedded system. In this paper, we design and implement a retargetable software debugger for a new 32-bit microprocessor. Our software debugger is based on GNU debugger (GDB) which is a widely used open-source debugger. We explain how to develop a retagetable software debugger for a new embedded processor rapidly. In order to develop a debugger rapidly, we extended only processor-dependent modules for register, memory and instruction set. And, we reused the processor-independent modules in the debugger. In the experiment, we tried to compare our software debugger with ARM AXD debugger to verify the debugger operation. The ARM AXD Debugger is well-known debugger for ARM processor.