An LED array device includes a plurality of LED units and a board for supporting the plurality of LED units. Each LED unit has a plurality of LED elements aligned straight in a predetermined pitch with a predetermined spacing between neighboring LED elements. The plurality of LED units are aligned straight with their end edges confronting each other such that an array of LED elements on one LED unit is in alignment with an array of LED elements on a next LED unit with the predetermined pitch being maintained. A spacing between an LED element positioned at the end of the alignment on the LED unit and the end edge of the LED unit is less than a half of the predetermined spacing.