The present study involved in-depth interviews to identify mental preparation strategies for best performance that Korean Olympic athletes in opened and closed sports used during their practice and training periods. 13 Olympic athletes in opened sports(badminton and table tennis) and 14 Olympic athletes in closed sports(shooting and archery) were selected by way of the purposeful sampling. They were ranging from the Olympic gold medalists to those of the World Championship. Mental preparation strategies of athletes were examined by prepared interview questions and their responses were all recorded. The recorded statements were inductively examined throughout the eight steps: making a script based on the record, poring over the script, classification and review, selection of quotation and data, categorization, check on the interviewees and classification, reducing the data, quantitative analysis. The result creates three major perspectives with regard to mental preparation for best performance: general preparation, training preparation, and cognitive preparation. General preparation included 27% of raw data which were classified into 7 categories and 4 dimensions(self and life management, responsibility, positive thought, social support). The training preparation consisted of 33% raw data which were classified as 8 categories and 3 dimensions(qualitative training, effort /beliefs, skill analysis). Cognitive psychological strategies included 40% raw data which were classified into 9 categories and 4 dimensions(imagery, goal setting, confidence, mental relaxed). Although some consistency existed in terms of dimensional factors, a lot of differences were also found in responses between athletes in opened and closed sports when comparisons were made by looking into quantitative categorical data. The differences in each mental preparation categories were discussed in terms of skill characteristics and Korean spiritual perspectives, and some suggestions were provided for future study.