This paper examines the behavior of investment in the Iranian economy emphasizing industrial investment and explains the factors affecting its decline. An examination of available statistics shows that the overall investment trend at constant prices (aggregate gross fixed capital formation and inventory change) in the country after an increase in the period 2004-2011 experienced a relatively considerable decline (a -23% growth in 2014, compared to 2011). Also, the share of total investment in GDP was decreasing in the period 2004-2014 (from 42.5% in 2004 to 33.4% in 2014). On the other hand, the volume of investment in exploitation licenses sharply decreased from 2008 to 2012 (from about 227 trillion Rials in 2008 to about 90 trillion Rials in 2012). In addition, after rising in a short period, the share of investment in exploitation licenses in total investment in Iran, fell sharply from 17.8% in 2008 to 3.9% in 2014. Major industrial investments made during the period 2005-2015 were limited to some specific resource-based activities.