This study had two objectives as follows: (1) to study the alcohol drinking behavior of parents of Secondary 6 students at Chaibadan Wittaya School, Lopburi, and (2) to report on the situation of alcohol consumption and related problems of parents of Secondary 6 students at Chaibadan Wittaya School, Lopburi. The sample group in this study consisted of parents of Secondary 6 students at Chaibadan Wittaya School, Lopburi, semester 1 of the academic year 2021, totaling 6 classrooms, number of parents 39 people. The study instrument was the alcohol drinking behavior questionnaire among the parents of Secondary 6 students at Chaibadan Wittaya School, Lopburi. The statistics used to analyze the data were averages. The results showed that, the study of alcohol consumption behavior of parents of Secondary 6 students at Chaibadan Wittaya School, Lopburi, by using the alcohol drinking behavior questionnaire of parents of Secondary 6 students at Chaibadan Wittaya School, Lopburi, it was related to the ability to control oneself by finding ways to relieve stress and discomfort without drinking alcohol at 46.15 percent. This is consistent with a study by Prapa and Usa, that predicted alcohol-free intentions among undergraduate students at a university in southern Thailand. It was found that the attitude was positively correlated with the intention not to drink alcohol at a statistically significant level (p-value < 0.01). The reference group's intent to quit drinking was correlated with the level of alcohol cessation, consistent with Eisen's theory of planned behavior. It states that the behavior conforms to the reference group in the practice of that behavior, with the reference group being an important determinant, the person's intention to act and whether the person commits any behavior. When the person has positively assessed the effect of the action and the person believes that the reference group is important to the practice of that behavior, that is, friends and family are important to the sample. The study found that the subjects prioritized their families when they thought they should reduce, and stop drinking alcohol. Their family members wanted them to focus on other activities instead of drinking alcohol in their spare time, such as exercise, sports, reading, etc., which accounted for 38.46 percent. Consistent with Nan and in accordance with the study of Prapa and Usa that examined factors that predict alcohol-free intentions of undergraduate students at a university in the south of Thailand. In their study, they found that the reference group's preference behavior was statistically positively correlated with the intention to abstain from alcohol. It can be discussed from the theory of planned behavior that reference group conformity is the perception of social norms or other people's beliefs that affect one's or one's actions. This perception is influenced by the people around them that the group is important to themselves. Literature review found that people with alcohol dependence seriously and permanently want to quit drinking because of family, partner, friends, etc. In the study, they were able to control themselves to do other activities instead of drinking alcohol in their spare time, which accounted for 35.89 percent. It is consistent with a study by Sukuma that examined the effect of a cognitive behavioral therapy program with social support on readiness to prevent relapse and non-relapse behavior among alcoholic patients. It was also found that social support can build mental readiness of patients to prevent alcohol dependence, by giving alcoholics an intention to prevent relapses and perceived their ability to prevent relapses. The Planned behavior theory states that one's efficacy to stop drinking alcohol is the perception of the person and the drinker's ability to stop drinking alcohol. For example, has patience, perseverance, does not give up, shows the ability to stop drinking alcohol. All of these will seriously affect the intention of implementing alcohol-cessation behaviors with a clearer goal to quit drinking. This results from having a positive attitude that drives the intention to behave according to reference groups such as family and friends, as well as the perception of the ability to clearly control alcohol abstinence behavior.