The electroluminescence (EL) spectra of white organic light emitting diodes (WOLEDs) with combination of red fluorescent and blue phosphorescent emitting layers were analyzed spectroscopically as a function of applied voltage. The red dopant was ( 2Z,2'Z)-3,3'-[4,4 ''-bis(dimethylamino)-1,1':4',1 ''-terphenyl-2',5'-diyl]-bis(2-phenylacrylonitrile) (ABCV-P) and blue one was iridium (III) bis[(4,6-difluorophenyl)-pyridinato-N,C2']-picolinate (FIrpic). Two devices with and without hole blocking layer (HBL) were fabricated. EL emission of device with HBL was shifted to a greenish white color compared to that of device without HBL. However, EL emission from both devices with and without HBL showed a rather low color temperature with Commission Internationale de L'Eclairage (CIE(xy)) coordinates from (0.416, 0.428) to (0.407, 0.431). Gaussian fitting of the EL spectra for fabricated WOLEDs supported that red emission was significantly affected by device structures and emission region became broader under high applying voltage.