PURPOSE: To obtain a device which can shorten the turnaround time by writing a piece of information by forming a semiconductor film, containing an impurity, used to connect source-drain semiconductor regions on a word line selectively and in a self-aligned manner with reference to the word line.

CONSTITUTION: In a read-only semiconductor memory device having series- connected MISFET rows Q1 to Q4, Q5 to Q8 which have been constituted of two or more word lines WL1 to WL4 extended mutually in parallel and of semiconductor regions 6a to 6l constituting a source region and a drain region, in the mutually adjacent word lines WL1 to WL4, formed in a direction nearly perpendicular to the word lines WL1 to WL4, a piece of information is written by forming a semiconductor film 7, containing an impurity, used to connect the semiconductor regions 6a to 6l on the second word lines WL1 to WL4 selectively and in a self-aligned manner with reference to the word lines WL1 to WL4. For example, a polycrystalline Si film 7 is doped selectively with an n-type impurity such as phosphorus; this impurity is transformed into a low- resistance n+ type; then, a piece of information is written.