We present the results of C^18^O(J=1-0) mapping observations of a 20'x18' area in the Lynds 1204 molecular cloud associated with the Sharpless 2-140 (S140) HII region. The C^18^O cube ({alpha}-{delta}-{nu}_LSR_) data show that there are three clumps of sizes ~1pc in the region. Two of these have peculiar redshifted velocity components at their edges, which can be interpreted as the results of the interaction between the cloud and the Cepheus Bubble. From the C^18^O cube data, clumpfind identified 123 C^18^O cores, which have mean radius, velocity width in FWHM, and LTE mass of 0.36+/-0.07pc, 0.37+/-0.09km/s, and 41+/-29M_{sun}_, respectively. Considering the uncertainty in the C^18^O abundance, all the cores in S140 are most likely to be gravitationally bound. We derived a C^18^O core mass function (CMF), which shows a power-law-like behavior above a turnover at 30M_{sun}_.