The electron spin resonance signals of $Bi_xCa_{1-x}MnO_3$ have been acquired for two samples of x=0.15 and 0.22. ESR signal of the sample of x=0.15 clearly shows signal shape change into Dysonian with g-value shift at around 165 K so that the charge ordering temperature can be identified. The general features of ESR signal of the two samples well correlate with magnetic susceptibility measurement and also confirm the validity of former investigations.