Introduction Recognising our strengths and using them in our daily lives is essential for improving our well-being. Recently this approach has been applied to work settings. Strengths Finder (SF) and Values in Action Inventory of Strengths (VIA-IS) are the most commonly used international instruments. However, these instruments were originally developed in Western countries and it is not certain whether the subordinate concepts of these instruments are suitable for people in the East. Therefore, this study was designed to develop an instrument for assessing the personal strengths of Japanese workers.

Methods All concepts within SF and VIA-IS and several other concepts that emerged as a result of brainstorming conducted by occupational health professionals in Japan were considered as subscales of the developing instrument. Thirty-three concepts were elicited, and subordinate items of each concept were developed. Of these, one concept was considered ambiguous, and therefore, 32 concepts with 264 items were used in the preliminary instrument. This was distributed to Japanese workers (n=971) between July and November 2011. After excluding 122 participants with missing responses, the data of the remaining 849 participants were used in the analyses.

Results After excluding 55 items that showed low factor loadings for each factor, 209 items were used for checking the reliability and validity of the new scale. Cronbach’s alpha mostly ranged from 0.64 to 0.84, except for one concept, ‘Shin’ (believe), which showed a Cronbach’s alpha score of 0.54. Moreover, factorial validity using confirmatory factor analyses revealed that most goodness of fit indices were within acceptable range (CFI: 0.78 to 0.99, SRMR 0.02 to 0.07).

Conclusion A new strengths instrument was developed through discussions with occupational health professionals and a preliminary study with Japanese workers. However, future studies are warranted because several concepts used in the instrument showed insufficient reliability or validity.