New result on direct CP violation from NA48

NA48 experiment aims at measuring the direct CP violation parameter $\Re(\epsilon '/ \epsilon)$ in the decays of neutral kaons with an accuracy of $2 \times 10^{-4}$. A result based on 1997 data sample has recently been published, confirming the occurrence of direct CP violation, with an error on $\Re(\epsilon '/\epsilon)$ of $7 \times 10^{-4}$. A new preliminary result based on the much larger 1998 data sample is presented. The principle of the measurement, the data analysis and the main systematics are discussed.