A vehicle speed control method calculates a present value KdB_c(a)_p of a corrected evaluation index of approach/separation condition by the following equation, and starts deceleration control when the determined present value KdB_c(a)_p exceeds a threshold value determined by a braking determining equation. In the deceleration control, a corrected target relative speed is determined based on an evaluation index KdB: KdB_c ⁢ ( a ) = 10 × log 10 ⁡ (  - 2 × VrGy - a × VrGy_offset Ds 3 × 1 5 × 10 - 8  ) wherein VrGy_offset, VrGy, a, Ds indicate a curve-time target speed, a difference between the curve-time target speed and a speed of a subject vehicle, a constant and a curve entrance arrival distance, respectively.