Anxiety surgery in patients has an impact on several perioperative aspects. The need for premedication and analgesic drugs is greater at the time of induction, the doses of anesthesia maintenance drugs are greater, including the need for postoperative analgesic abortion also increase in addition to the impact of the extended recovery phase so that it can increase the length of treatment which gives the effect of increasing the cost of hospitalization. The incidence of preoperative anxiety from various studies around the world varies greatly from 60% to 90%. Indonesia does not yet have data on the incidence of preoperative anxiety in patients undergoing elective surgery. The incidence of preoperative anxiety in Indonesia is thought to be quite high. Purposes : Develop valid and reliable preoperative patient anxiety assessment instruments. Method : Conduct preoperative anxiety measurement instruments from literature studies, conduct psychometric test instruments on respondents. The instrument that was tested was used to measure the anxiety of 65 respondents then their validity and reliability were assessed. The results of measuring anxiety with INPOAS compared to the HAM-A anxiety instrument were then tested by the Cohen's Kappa. Result : Respondents involved as many as 65 people, 0.011 determinant test results that indicate each statement is interrelated.All statements on the INPOAS scale are valid with Corrected Item-Total Correlation r total 0.989> 0.254. All statement items have a Cronbach Alpha value ()> 0.70 with the Cronbach Alpha value () overall 0.812 Conclusion : Indonesian Preoperative Anxiety Scale (INPOAS) is a valid and reliable instrument for measuring preoperative anxiety