  We have been conducting a exoplanet search survey using Bohyunsan Observatory
Echelle Spectrograph (BOES) for the last 18 years. We present the detection of
exoplanet candidate in orbit around HD 18438 from high-precision radial
velocity (RV) mesurements. The target was already reported in 2018 (Bang et al.
2018). They conclude that the RV variations with a period of 719 days are
likely to be caused by the pulsations because the Lomb-Scargle periodogram of
HIPPARCOS photometric and Ha EW variations for HD 18438 show peaks with periods
close to that of RV variations and there were no correlations between bisectors
and RV measurements. However, the data were not sufficient to reach a firm
conclusion. We obtained more RV data for four years. The longer time baseline
yields a more accurate determination with a revised period of 803 +/- 5 days
and the planetary origin of RV variations with a minimum planetary companion
mass of 21 +/- 1 MJup. Our current estimate of the stellar parameters for HD
18438 makes it currently the largest star with a planetary companion.
