The aim of this research was to design and test a model of the effect of HEXACO Personality Variable on Happiness with mediating Attribution Style. In this research HEXACO Personality Variables was considered as predictor of Happiness. In addition Attribution Style was considered as mediator of relationship between predictor and dependent variable. The instruments which used in this study include HEXACO Personality Inventory, Oxford Happiness Questionnaire, and Attribution Style Questionnaire (ASQ). Data collected from 445 employees of an industrial Company. That selected via simple random sampling method. Structural equation modeling through AMOS 18 and SPSS 18 software package were used for data analysis. The indirect effects were tested by Bootstrap procedure. Results indicate that Exogenous Variables Honesty-Humility, Extraversion, Conscientiousness and Openness to Experience have a significant direct effect and Emotionality and Agreeableness have a not significant direct effect. Also indicate that Relation between predictor variable (Honesty-Humility, Extraversion, Conscientiousness, Openness to experience) whit Happiness through the Attribution style was mediator.