This study investigates the construction of one’s self-perception as a writer, and to develop a proper scale to measure elementary school students’ perceptions of themselves as writers. To validate this scale, an exploratory factor analysis was carried out based on the responses of 116 students in elementary grade 6. This resulted in 31 items representing 3 sub-factors: “social expectation and evaluation,” “progress in writing,” and “physiological states.” The total variance for the three factors was 67.269%. These factors were classified into social, cognitive, and affective factors; their relationships were then identified. The final three-factor scales were administered to 656 elementary school students in grades 4, 5, and 6. Results from a confirmatory factor analysis showed that the model with three factors had a reasonably acceptable applicability. It was found that the Writer Self-Perception Scale (WSPS) with three factors was a reliable and valid measurement method. This study is expected to provide useful information regarding students as writers, and to contribute to their writing instruction.