We demonstrated the effectiveness of coupling charged nanospheres with the genetic field effect transistor (FET) for highly sensitive detection of DNA molecules. The large amount of negative charges on the gate insulator induced strongly electrostatic interaction with electrons in silicon by field effect, resulting in the bigger shift of the threshold voltage. The charged nanospheres-coupled genetic FET allowed highly sensitive detection of the target DNA as low concentration as 100 aM (10 zmol). The genetic FET platform combined with charged nanospheres is suitable for a simple, sensitive, accurate and inexpensive system for DNA analyses.