A variable valve timing control apparatus, includes a drive-side rotary member, a driven-side rotary member, a partition portion arranged at least one of the drive-side rotary member and the driven-side rotary member to partition a fluid pressure chamber into an advanced angle chamber and a retarded angle chamber, a seal member arranged at a portion of the partition portion, which faces the other one of the drive-side rotary member and the driven-side rotary member, the seal member avoiding a hydraulic fluid from leaking between the advanced angle chamber and the retarded angle chamber, and a biasing member biasing the seal member, wherein at least one of the partition portion and a facing surface of the other one of the drive-side rotary member and the driven-side rotary member facing the partition portion is defined by an inclined surface of a tapered portion.