We theoretically studied the electron density dependence of the electric field enhancement effect caused by the localized surface plasmon resonance in heavily-doped InAs/GaAs quantum dots (QDs). The resonant wavelength of the field enhancement factor in spherical and semi-ellipsoid QDs shows a shift toward shorter wavelengths with increasing the electron density at mid-to-near infrared wavelengths. Semi-ellipsoid QDs have a resonance at a longer wavelength than spherical QDs and show stronger electric field enhancement. Furthermore, the multiple resonant wavelengths appear in semi-ellipsoid InAs/GaAs QDs due to the lowered symmetry, which is promising for the electric field enhancement at the infrared wavelength for increasing the energy conversion efficiency of photovoltaics.