This thesis presents the design and development of an invisible guitar - a gesture recognition system as a guitar model and MIDI controller. The goal of this work is to build a virtual guitar as a music instrument which enable user to learn music easier as well as become MIDI controller to control a software synthesizer. The design and development process will be described step-by-step from the concept phase until the testing and analysis phase. The process covers the implementation of mass spring damper system as a physical model of a guitar string. Moreover the analysis and comparison of real guitar sound as the reference to simulate the behavior of the model is also involved and described. As the result, this system use micro controller and several sensors to recognizes hand gesture as the input and simulate several guitar playing techniques such as string plucking, strumming, and bending. The output of the system is a MIDI message which can control software synthesizer to produce sound. Furthermore, the system is analyzed to test its playability and to prove that the output can simulate the characteristic of a guitar and its playing technique.