This study aimed to determine how 15 weeks of Tai Chi training affected attention and brain waves. Thirty-six university students (mean age = 24.27 years; SD = ±1.054) participated in this experiment. Participants practiced form postures from the first section of form 85 of the traditional Yang style of Tai Chi Chuan. The Frankfurt Attention Inventory (FAIR) was used to assess each participant’s level of attention. The sensorimotor rhythm (SMR) power analysis demonstrated that participants in the Tai Chi group show higher SMR power than the control group. This study showed that Tai Chi Chuan increases theta and alpha waves by relaxing the body and mind, as well as through soft and slow movement and deep breathing. It reduces fast beta waves, which stabilizes the brain and improves attention. FAIR results showed that 15 weeks of Tai Chi training improved selective ability, control index, and persistence index. These findings suggested that Tai Chi is an exercise that helps improve attention.