Background : Demonstrations are the statements of protest that expressed by a group of people in public. From the several cases that occurred, many of them ended in riots. For overcoming this matter, Indonesian Police has a special unit that its duties must be in accordance with existing regulations so good performance can be achieved. Emotional maturity and adaptation are two of several factors that influence a person’s performance so it needs to be examined wether there is a relationship between emotional maturity and adaptation to the performance of members of Brigade mobile during securing a demonstration. Methods : The design of this study was a non-experimental quantitative research (observational) with a cross sectional approach. Data collection was carried out at the Brimob Gondowulung Company on Jl. Imogiri Timur in September 2018 using a questionnaire filled out directly by 74 of respondents. The data were analyzed using Chi Square statistical tests. Result : Among the total of 74 respondents, 62 people (83.8%) had a positive level of emotional maturity, 12 people (16.2%) had an unstable level of emotional maturity (sometimes positive sometimes negative) and no PHH members had a negative level of emotional maturity. Then for the adaptation ability variable was found that 56 people (75.7%) had a high level of adaptation, 14 people (18.9%) had a moderate level of adaptation and the remaining 4 people (5.4%) had a low level of adaptation. For the performance variable, 58 (78.4%) had good performance, 14 people (18.9%) had sufficient performance and 2 people (2.7%) had poor performance. The statistical test of the relationship between emotional maturity and the performance of members of PHH SAT Brimob Polda DIY showed significant results (p = 0.003), and the statistical test of the relationship between adaptability and the performance of members of PHH SAT Brimob Polda DIY showed significant results (p = 0.018). Conclusion : There is a significant relationship between the level of emotional maturity and the adaptation of the performance of members of PHH SAT Brimob Polda DIY.