A valve opening/closing timing controlling apparatus includes a housing member 3 rotatable together with a timing gear 110 (drive member), a rotor member 2 rotatably assembled with the housing member 3, a vane 70 portion of the rotor member forming, within the housing member 3, a phase-advanced oil chamber R1 and a phase-lagged oil chamber R2, the rotor member being rotatable together with a cam shaft 10, a torsion coil spring 55 for urging the rotor member 2 relative to the housing member 3 in a phase advancing direction, and a phase-advanced oil passage (hydraulic circuit) 65 or a phase-lagged oil passage (hydraulic circuit) 66 a hydraulic circuit for controlling feeding/discharging of work oil to or from the phase-advanced oil chamber R1 or the phase-lagged oil chamber R2. The torsion coil spring 55 has one end 55a thereof fixed to the housing member 3 and the other end 55b thereof fixed to a projection 28 provided on the rotor member 2.