Background: Adrenaline auto-injectors (AAIs) are not used correctly by patients and their caregivers because of a lack of training. The aim of this study was to determine how to help patients maintain proper use of AAIs. Methods: Patients prescribed AAIs or their caregivers were recruited. At enrollment, they were asked to demonstrate use of a ‘trainer’ device, and they were given a calendar as a diary. They were asked to mark the days they practice for a year. After one year, their performance was re-evaluated. Their skills were evaluated in five steps that consisted of a) how to hold the AAI, b) removing the cap, c) selecting the mid-anterolateral thigh as the correct site of injection, d) holding firmly in place for 5 seconds, and e) massaging after injection. The primary endpoint was the percentage of participants that correctly used the AAI one year after enrollment. Results: A total of 102 participants were enrolled. At enrollment, of the 82 participants who had previous AAI prescriptions, 38 (46.3%) used it correctly. Except for evaluation items d) and e), 55 of 82 (67.1%) used it correctly. Ninety-seven participants could be confirmed after one year, and 81 of them (83.5%) used the AAI correctly. Conclusion: Distributing the diary was effective in maintaining AAI skill. It is thought that the diary helped participants maintain their motivation to practice using the AAI.