As well as supreme image quality realized by specialized paper, industrial and office printing markets demand uncoated general papers compatible with both offset printing and non-impact printing. The present work aims at clarifying the behavior of a micro-liquid droplet of water-based ink-jet inks or simply water absorbed into uncoated paper. In the experiment, laboratory handsheets were prepared by adding alkyl ketene dimmer (AKD) as a sizing agent at different levels of water repellency; none, 0.05, 0.10 and 0.20 % on dry pulp mass. The landing action and the absorption into paper of micro-droplets of water ejected from an ink-jet head were recorded by the microscopic high-speed video camera system every millisecond. The period of time between the landing and the completion of absorption was defined as “micro-sizing degree”. The micro-sizing degree was approximately 2 to 3 ms up to 0.10 % AKD addition. It is lower than that of commercial silica-coated ink-jet papers which was approximately 8 ms although silica-coated papers are known to absorb water very quickly. However, the micro-sizing degree was approximately 45 ms for the handsheets of 0.20 % AKD addition. This result implies that the water-repellency by AKD is distributed over fiber surfaces so homogeneously that micro-water droplets of diameters of as small as a few micrometers are absorbed stably at similar rates.