The present study aims to verify whether the perception of irony occurs after pragmatic insincerity is detected from the speaker's perspective or from the listener's egocentric perspective. Under the manipulation of shared common ground (CG) between the listener who had ironic environment and the speaker, effects of cognitive load on irony comprehension were explored. In Experiment 1, participants read passage and rated the degree of perceived irony with⁄without cognitive load. In Experiment 2, participants also had to judge whether the utterance was irony or not as quickly as possible. On low-CG condition, cognitive load increased the degree of perceived irony (Experiment 1) and decreased the reaction time of irony judgment (Experiment 2). These results showed that participants didn't inhibit the unintended ironical meaning because they were unable to consider common ground under cognitive load. On high-CG condition, cognitive load affected neither the degree of perceived irony nor the reaction time of irony judgment. It was suggested that listeners initiate the processing of ironical meaning when they notice the pragmatic insincerity from their egocentric perspective, not when they recognize it from the speaker's perspective.