According to the present invention the storage stability of a diazo based imaging element can be improved by controlling the amount of free water in the imaging element. Thus the present invention provides an imaging element comprising on a support a hydrophilic layer containing a hydrophilic (co)polymer or (co)polymer mixture and having been hardened with a hydrolyzed tetraalkyl orthosilicate and a light sensitive layer containing a diazo resin or a diazonium salt characterized in that the total amount of free water in said imaging element satisfies the following formula (I):FW (g/m.sup.2).ltoreq.0.0043 * WS (g/m.sup.2)+0.46 (g/m.sup.2) (I)wherein FW represents the amount of free water and WS represents the weight of the support of the imaging element.