Objective: We quantitively and qualitatively evaluated whether non-medical staff display efficacy stability in performing basic life support (BLS) techniques in which they receive instructions. Method: Eleven staff members individually performed BLS techniques using a feedback device that provided immediate evaluation and instruction. Each staff member subsequently performed the BLS techniques again and underwent reevaluation. This series of performance, evaluation, instruction, subsequent performance, and reevaluation constituted one training sequence. The training sequences were performed by each participant at 0, 6, 12, and 18 months to examine the longevity of the training. Furthermore, at the beginning and after the study, each staff member reported their knowledge of BLS procedures and preparation for BLS, and the results were compared. Results: Training cumulative effects were observed in chest compression depth after 6 (p=0.012) and 12 (p=0.040) months and in recoil after 6 (p=0.023) and 18 (p=0.035) months, respectively. Moreover, the effect lasted for 6 months after a single instruction session. The single training effect lasted for at least 6 months, while neither compression tempo nor chest compression fraction (CCF) significantly changed the training efficacy during the study period. Most staff members were able to perform the necessary techniques after at least one sequence of practical instruction; thereafter, the effectiveness of instruction was maintained. However, the initial power-on of the automated external defibrillator operation was not reliable until 18 months (6/11). Conversely, in the knowledge survey regarding BLS, all staff members had correct knowledge of all items after the study. In the attitude survey, the number of staff members who answered, “I can do it with confidence” increased for all items after the study. When there had an opportunity to perform BLS, the number of staff members who had a positive impression increased after 18 months, while those who had a negative impression decreased but had no significant change. Conclusion: Compression depth and recoil showed short-term efficacy, the single training effect lasted for at least 6 months, and a cumulative effect of instruction was observed. In contrast, tempo and CCF did not significantly change the training efficacy throughout the study period. Participants were generally able to correctly understand and perform BLS techniques and techniques that could be qualitatively evaluated. Furthermore, it was possible to give participants confidence in BLS techniques. The quantitative evaluations using a feedback device contributed to BLS instruction longevity. On the other hand, after 18 months of training, if BLS could be performed, the impression of staff members had no significant change.