One of the most discussion is considered in recent years is management decision about expense. In traditional way, profit analysis models have assumed expense behavior depends on production and sales volatility. Although researches which are done in the 90s show holding this assumption is not true. So these kinds of conclusions cause trying to answer why such behavior is seen. This Research Examines the Relationship Between prior sales Changes and Asymmetric Expense Behavior and Positive or Negative Management attitude effect on it. in order to measure of asymmetric expense behavior, backing research literature, current relationship between sg&a changes and sales changes is utilized; sales changes related to two period ago is calculated as a proxy for management attitude too. So 105 corporations' financial data listed on tehran stock exchange (tse) are collected (1050firm-year) during 1383 to 1392 using certain criteria. OLS – fixed effect method is run to analysis data. the result reveal that expense behave in asymmetric manner; prior sales changes has positive relationship with expense asymmetric behavior by reducing uncertainty; and management attitude can moderate the effect of it on Asymmetric Expense Behavior. As a Consequence, Positive Attitude Strengthen the positive Relationship between Prior sales changes and Expense Asymmetric Behavior and Negative Attitude causes more Symmetric Expense Behavior.