The purpose of this research is to analyze the structure of academic writing ability of first-year and second-year university students—students who are at the stage of general education. Practitioners and scholars have analyzed students’ writing ability; however, analyses on university students have been limited to those conducted under subjective criteria based on practices in a particular classroom or a certain course. Studies using objective methods have typically been limited to the level of junior-high and high-school students. Thus, the present study analyzed a larger sample of students’ papers at the university level using an objective methodology—factor analysis. 384 assignment papers from various courses written by first-year and second-year university students were evaluated using thirty-five criteria. The criteria were all based on the skills of academic writing without regard to specific fields. Factor analysis indicated five factors relevant to students’ academic writing ability: words and sentences, content, paragraphs, overall organization, and references. This five-factor structure of students’ academic writing ability can be applied in designing an academic writing course as well as in developing a rubric for assessing students’ academic writing at the stage of general education.