From the perspective of positive psychology, the study and measurement of subjective well-being has popularized a growing interest towards variables such as affective perception. In an attempt to explain and evaluate the affective structure in positive terms (PA) and negative terms (NA), PANASN affect scale (Sandín, 2003) constitutes the version adapted for children and teenagers of the Positive and Negative Affect Schedule (Watson et al., 1988). Opposite to the confirmatory study made in teenagers by Sandín (2003), this paper proceeds to analyse the internal structure and reliability of the above mentioned questionnaire after being administered to 636 students aged between 6 and 14 years. An instrumental type of research methodology was carried out. The instrument used was the Positive and Negative Affect Scale for Children and Adolescents (PANASN). While confirmatory and exploratory analysis show an appropriate adjustment, these properties tend to fade when three or four factors are considered. In response to this, we reflect on the need to consider certain aspects of improvement in content and form, which are essential if we want to use said instrument with primary education students.