Background and aim: Psychosis is a mental disorder resulting in high disability impacts. Many studies show that early detection of prodromal symptoms may improve prognosis. Psychotic prodromal symptoms may mimic other mental health conditions such as depression, anxiety or learning difficulties. The aim of this study was to analyze validity, reliability, sensitivity and specificity of the Prodromal Questionnaire Brief Version (PQ-B) Indonesian version to detect psychotic prodromal symptoms. Method: The PQ-B was translated into Indonesian then back-translated into English. Subjects included in this study were 50 children and adolescent psychiatric patients from Cipto Mangunkusumo National Hospital, aged 10–18 years old. Validity measurement was performed by comparing the total score and distress score of PQ-B with the categorical scale of Structured Interview for Prodromal Symptoms (SIPS) as the gold standard using Spearman correlation. Total scale and subscale reliability were examined using the Cronbach's Alpha. Results: Analysis with Spearman correlation showed significant results of both PQ-B total score with diagnosis of SIPS (r = 0.374 and p = 0.007); and PQ-B distress score with diagnosis of SIPS (r = 0.400 and p = 0.004). Cronbach Alpha coefficient was equal to 0.853 for all scales. The sensitivity of the PQ-B in the Indonesian language is 70%, and the specificity is 72%, whereas, in the original language (English), the sensitivity and specificity is 88% and 68%. Conclusion: This study provides evidence of good validity, reliability, sensitivity, and specificity of PQ-B Indonesian language to detect prodromal symptoms of those who seek help in the psychiatric outpatient clinic.