A variable damping force valve of a shock absorber includes a variable valve for varying damping force by a plurality of flow passages connected to the shock absorber and a solenoid actuator for actuating the variable valve. The variable valve and the solenoid actuator are coupled with each other by a coupling ring in a single body, and the coupling ring has an open portion, thereby being coupledto an inside of the variable valve by elastic deformation or restitution thereof to fix the solenoid actuator and the variable valve. Accordingly, there is an advantage in that the variable valve andthe solenoid actuator are assembled in one-touch manner by providing the coupling ring, thereby simplifying an assembling process.