Preparation and use of synthetic monosaccharides, disaccharides, trisaccharides, tetrasaccharides and pentasaccharides useful for the preparation of synthetic heparinoids. The droplet ejecting head maintenance units are arranged in a group in a movable platen as a maintenance-unit installing section. The method of producing hydroxyalkylacrylate of the present invention involves producing hydroxyalkylacrylate using the aforementioned apparatus for producing hydroxyalkylacrylate. A resin layer is arranged between the chip and the protection plate to absorb light having a predetermined wavelength.