The purpose of this study is to develop and test instrument for measuring nurses’ preparing behavior about writing case report. The study proceeded in two phases. In phase one, the researchers synthesized suggestions from literatures and experienced practitioner to establish the instrument content validity. The instrument had good reliability on 35 nurses in pilot study ( cronbach’s α = .90 ; test-retest correlation coefficient = .58, p < .001). In phase two, the subjects consisted 454 clinical nurses. Based on the results of factor analysis, four factors were extracted from 20 items and accounted for 63.68% of the total variance. The coefficients of the cronbach’s α for the main scale and it’s subscale were .74 - .91. The results showed that the instrument for “Nurses’ Preparing Behavior of Writing Case Report” possessed acceptable content validity, construct validity and internal reliability. Implications of these results were discussed.