Breakthrough pain (BTP) is temporary and considerably severe. Thus, patients with BTP are more likely to perceive pain-related stimuli as a threat than those without BTP. The purpose of this study was to investigate the differences in attentional bias in patients with and without BTP. This study recruited 17 patients and 25 patients with and without BTP, respectively, from among patients with chronic pain at a university hospital in Suwon, Republic of Korea. The participants’ eye movements were recorded using an eye tracker during a free viewing task that features sensory pain-neutral, affective pain-neutral, and neutral-neutral word pairs. Two-way ANOVA(group*word type) was conducted on the attentional bias indices. The results were as follows: First of all, looking at the attentional-orientation index, it was found that in the time taken until the first fixation, patients with BTP were more vigilant towards sensory pain words and affective pain words than patients without BTP. In addition, during the first 250ms, patients with BTP was more vigilant towards affective pain words than patients without BTP. Finally, looking at the attentional-maintenance index, in the total time for taking the Area Of Interest (AOI), the patients without BTP showed more difficulty with distraction for sensory pain words than patients with BTP. The patients with BTP showed more difficulty with distraction for affective pain words than the patients without BTP. The results of the study provide the need for correction of the existing vigilance-avoidance pattern, and they suggest that characteristics, such as the presence or absence of BTP and word type in chronic pain patients, should be considered in the attention bias modification (ABM) program.