In a case of writing to a trap type non-volatile memory cell that includes: a laminated insulating film, containing a charge accumulation layer, that is formed on a semiconductor substrate where source, drain and well regions are formed; and a first gate electrode formed on the laminated insulating film, charge injections that are carried on a single memory node multiple times under two or more different writing conditions, the writing condition is a combination of a well voltage applied to the well, a drain voltage applied to the drain and a gate voltage is applied to the first gate. Thereby, it is possible to form a trapezoid-shaped electron distribution in the charge accumulation layer, and thus prevent the charge retention characteristic from deteriorating.