Objective:This study reports a randomized controlled trial of the effect of a job crafting intervention program on work performance and job crafting (as secondary outcomes) among Japanese employees.Methods:Participants who satisfied the inclusion criteria were randomly allocated to an intervention (n = 138) or a control group (n = 143). Outcomes were measured at baseline and at 3-month and 6-month follow-up in both groups.Results:For the whole sample, the job crafting intervention program showed a nonsignificant effect on work performance and job crafting. However, the program showed a significant effect on these outcomes among younger participants (under 36years old).Conclusions:The job crafting intervention program may not be sufficiently effective to improve work performance and job crafting for the whole sample of participants. However, it may be efficacious for younger workers.