This microlens array comprises hexagonal field diaphragms in inverted-image-forming positions, i.e., microlenses, a plurality of which are arranged in the direction perpendicular to a direction of scanning, and from which rows of microlenses are configured. Further, for three rows of microlenses, microlens rows are arranged with offset by (a length S) in a direction perpendicular to the direction of scanning such that triangular portions of the hexagonal field diaphragms overlap in the direction of scanning. Furthermore, microlens row groups, which are configured from three microlens rows, are arranged with offset in the direction perpendicular to the direction of scanning in increments of a minute amount of shifting F (for example, 2 μm). Thereby, this scanning exposure device using a microlens array is capable of preventing exposure ununiformity even in the direction perpendicular to the direction of scanning.