A power generation control apparatus in a vehicle includes: a power generator generating power when driven by an internal combustion engine; an electric storage apparatus charged by the power generator; a current sensor measuring a charge and discharge current value; an SOC computation portion estimating an SOC in the electric storage apparatus on the basis of the measured charge and discharge current; a generation voltage computation portion determining a generation voltage of the power generator so that the SOC in the electric storage apparatus becomes a target SOC; a target SOC computation portion setting the target SOC; and a generation cost computation portion calculating an amount of consumed fuel per unit generation output on the basis of an operating point of the internal combustion engine. The target SOC set by the target SOC computation portion is changed according to the calculated amount of consumed fuel per unit generation output.