The invention provides a negative photosensitive resin composition, an electronic device and a polymer, and the balance between the resolution and the time spent by the formation of a pattern is excellent. The invention provides a negative photosensitive resin composition including the polymer and an optical free radical polymerization initiator, the polymer comprises a repeated unit of the below (1) and (2a), R5 of the formula (2a) is provided with a free radical polymeric group and an organic group with the number of carbon atoms of 2-18. (In the formula (1), R1, R2, R3 and R4 are respectively and independently organic groups with the number of hydrogen or carbon atoms of 1-30, and n is 0, 1 or 2).
Negative photosensitive resin composition, electronic device and polymer