Deinkability of inkjet printed waste papers was assessed by flotation deinking method with fatty alcohol derivative as a deinking agent. Though inkjet inks are easily detached from the waste paper, detached inks are too small to be rejected out in the flotation cell. In order to increase the flotation efficiency, the kneading process was omitted and fatty acid or new ink collector was added in the flotation cell. Consequently, the brightness of the deinked pulp sheet obtained after flotation increased markedly. From these results, when the collected waste papers are only inkjet printings, inkjet inks are said to be deinkable by the current deinking line. But practically, waste papers are mixtures of digital and offset printings, since they are not classified by their printing types. When the electrophotography printed waste papers are deinked, strong shearing power is needed, consequently kneading cannot be avoided. It is necessary to establish the deinking method and develop the deinking agents and/or systems for mixed ondemand printings in early stage.