The construction industry has great importance for the economy, especially in developing countries. While having such great importance at macro level, there are many uncertainties for the industry to overcome. Productivity is one of the most important uncertainties in the industry. Most of the companies in the industry do not have any performance measure or efficient criteria for the technical personnel, and the work outcomes of the technical personnel are not quantifiable. This study aims to identify and rank the multi-causal factors affecting the productivity of technical personnel in the construction industry. For this purpose, a detailed questionnaire survey was taken among 400 professionals in the construction industry. Kaiser-Meyer-Olkin measure of sampling adequacy, Barlett's test of sphericity which makes Cronbach's alpha, and reliability tests were conducted on the results of the questionnaire survey. The relative importance index was used for ranking the importance level of the factors. The top nine factors affecting technical personnel's productivity are listed as Management, External and Owner Related, Motivational, Financial, Working Condition, Welfare and Comfort, Lacking Resources, Personal and Workload factors in the study, and 47% of these factors affecting technical personnel's' productivity are expressed by management factors. The most important factor groups after the management factors are working conditions, human factors and external factors, respectively. It is thought that the results of this research will shed light on for further research that focus on maximizing the productivity of technical personnel in the construction industry.