Factors affecting digital skills were analyzed using open data from the International Adult Power Survey (PIAAC: Programme for the International Assessment of Adult Competencies) conducted in 38 countries in 2011-2018. The number of correct answers (15,702 cases from 25 countries) to questions on problem solving ability (PSTRE: Problem Solving in Technology-Rich Environments) utilizing information technology (IT) that are supposed to reflect digital skills were used. The analysis procedure was as follows. 1. Comparison of the correct answer rates for PSTRE tasks in each country. 2. Factor analysis of 63 questions selected from background surveys (such as daily media use). 3. Regression analysis using the factor scores for selected factors, age, gender and educational background as the explanatory variable, and the number of correct answers to PSTRE for each respondent as the objective variable. The results for all 25 countries, Japan, and three countries in Northern Europe (Nordic countries) were grouped and analyzed. The results indicated that the correct answer rate for each question varied between countries, and the factors affecting the number of correct answers for the question varied between the three groups. In particular, age and educational background factors affected PSTRE in all groups, and there was no significant difference between genders in Japan and the three Nordic countries.