Cognitive bias means a tendency to make irrational decisions about other people and situations. Cognitive biases are really common since they are produced by human nature. Habits, educational background, experience, business culture and similar components reflect cognitive bias of decision-maker in organizational decisions. Knowledge level and automatic behaviors of managers and routines are examples of cognitive biases in strategic decisions. Shortly, especially intuitional decisions made by managers are influenced by these biases. Many patterns for bias have been defined in the current literature. The most frequently encountered types of bias in organizational decisions are as follows.