Positive mental health is a complex construct that is related to the optimal functioning of the person. It comprises a set of qualities aimed at the development of the individual's potential. The Positive Mental Health Scale is one of the most used instruments to evaluate it, however, the antecedents indicate inconsistencies regarding its internal structure. The objective of this study was to analyze the psychometric properties of the Positive Mental Health Scale in Arequipa-Peru. 3,933 people partici-pated, 50.3% were women and 49.7% were men, including from adolescents to the elderly. The evaluation by CFA of the original structure showed poor fit indices, so the dimensionality had to be evaluated and a new structure had to be proposed. For which the sample is divided (n1 = 1,966 and n2 = 1,967). In the first, an EFA was applied and in the second, it is validated by means of a CFA. Three factors were found and it is con-cluded that it has a good fit (χ2 (431) = 2,473.378; CFI = .959; TLI = .956, RMSEA = .049; SRMR = .051). The internal consistency showed values greater than .81. Finally, the equivalence of the measurement according to sex was evaluated, finding that the instrument presents measurement invar-iance.