The study aims to explore whether the treatment using fNIRS-based neurofeedback training for children with attention-deficit/hyperactivity disorder (ADHD) is useful. Furthermore, the study hopes to evaluate whether the use of virtual reality (VR) technology will have an impact on the treatment's effectiveness. The program includes the following components: Participants will be randomly assigned to one of three intervention groups: the neurofeedback with virtual reality (VR) group, the 2D neurofeedback group (with no VR technology applied), and the VR without neurofeedback group. All participants will complete academic-related tasks in simulated lessons. Participants in the VR neurofeedback group will wear VR goggles and a neurofeedback device that measures blood oxy-hemoglobin levels in brain cortical tissue and provides feedback via visual images or auditory sounds to the participants. Those in the 2D neurofeedback group will use a computer to complete the tasks, with all other settings (e.g., neurofeedback settings) remaining the same. The VR without neurofeedback group will wear VR goggles to complete tasks, but without the neurofeedback component. All participants will complete a total of 16 training sessions over 8 weeks (twice a week), with each session lasting approximately 35 to 60 minutes. To investigate the intervention's effectiveness, children will be asked to complete a set of cognitive tests covering inhibitory control, attention, and working memory before the intervention (i.e., Time 1), immediately after the 8-week training (i.e., Time 2), and 2 months after the training (i.e., Time 3, a 2-month follow-up). The assessment will take around 1 hour and will be conducted at the laboratory at the University of Hong Kong. Additionally, parents and teachers will be asked to complete a questionnaire assessing children's behavior at home and at school at three time points.