To suppress vibration due to a fuel injection device with a simple constitution in a mounting structure of the fuel injection device.

A mounting structure of a fuel injection device has a plurality of fuel injection devices 25, a plurality of injector holes 23 formed on a cylinder head 2 and respectively receiving one end of the fuel injection device, a nozzle arm 41 for locking parts projecting from insertion holes of two fuel injection devices adjacent to each other, a bolt 43 penetrating through the nozzle arm, and engaged with a female screw hole 42 formed on the cylinder head to fasten the nozzle arm to the cylinder head, and a weight member 44 having a weight-side insertion hole 58 to which a shaft portion 43B of the bolt is inserted, and held between a head portion 43A of the bolt and the nozzle arm.