Microchips are a useful means for individual identification, and they are hoped to become popular for reuniting separated companion animals (dogs and cats) with their owners. However, pet owners’ views and thoughts regarding microchip mounting is not clear. This study aimed to reveal the predictors of behavioral intentions toward microchip mounting using questionnaires based on the Theory of Planned Behavior (TPB). The results revealed 306 valid responses [47.4% of owners (dog owners 51.7%, cat owners 42.1%, both owners 6.2%) and 52.6% of non-owners], in which 35 owners (28.4% of dogs and 8.8% of cats) had already mounted a microchip to their own pet. Pet owners scored significantly higher on subjective norms than non-owners on the TPB items. It was found that TPB explained the differences in attitudes between respondents and their use of microchips and their behavioral intentions for microchip adoption. Finally, this study also suggested that veterinarians would be the key to further dissemination of microchips.