This research was based on the very low competency of soft skills acquired by graduates of Mechanical Engineering of Vocational High School performed at workplaces. The objectives of the research were to identify specific soft skills that should be mastered by students of Mechanical engineering and to develop instructional models to teach the soft skills. The research consisted of two parts:(1) to identify soft skills needed by students of Mechanical by using engineering survey and questionnaire,(2) to develop instructional models to teach soft skills, followed a modified Borg & Gail design through R&D research design. The instructional models were called six principles of soft skills instructional models, or MP2S6P. The effectiveness of the model of an experiment was conducted through a posttest-only control group design. Based on the research findings, there are 27 soft skills that should be mastered by students of Mechanical Engineering. The application of the developed MP26P model resulted in significant achievement which was better than by using conventional instruction towards the students at Mechanical Engineering Department. The teachers and students have positive perceptions about the MP2S6P model. Based on the results, it can be recommended that MP2S6P should be developed and used in teaching necessary soft skills in Vocational High Schools.