This research aimed 1) to study levels of transformational leadership innovative climate knowledge management systems innovative work behaviors and firm performances 2) to investigate causal relationship of transformational leadership innovative climate knowledge management system as well as innovative work behaviors which influenced on performances of the Medical Device Business in Thailand 3) to examine relevance of those variables along with causal relationships of the antecedents affecting performance of the Medical Device Business in Thailand to empirical data. Data were collected from 312 middle level managers in Medical Device Business in Thailand by using questionnaires as a research instrument. All of the data were analyzed using Structural Equation Model. The analysis of correlation coefficient model showed that the latent variables significantly related to one other at statistical level of 0.001. The analysis of structural equation model (SEM) revealed that the model was completely compatible with the empirical data and the hypothesis. (GFI = 0.933 CFI = 0.972 RMSEA = 0.078 RMR = 0.018) The findings also showed that transformational leadership significantly affected innovative work behaviors at statistical level of 0.001. Similarly innovative climate significantly affected innovative work behaviors at statistical level of 0.001. Likewise knowledge management system significantly affected innovative work behaviors at statistical level of 0.001. Finally innovative work behaviors significantly and directly affected the firm performance at statistical level of 0.05.