Interoception, the internal perception of bodily states such as heartbeat and hunger, plays a crucial role in shaping cognitive and emotional states. Given that previous studies have shown postural control influences cognitive and emotional processing, understanding how postural control influences interoception could contribute to reveal the neural basis of its effects on cognition and emotion. Here, we aimed to investigate the effects of posture on interoception by using heartbeat evoked potentials (HEPs), which are event-related potentials that reflect the cortical processing of heartbeats.The study involved 21 healthy male participants. They were asked to relax while sitting in a chair (sitting condition) or standing (standing condition). 64-channel electroencephalogram (EEG) data and electrocardiogram (ECG) data were collected. The EEG data were epoched to analyze HEPs by the timing of the R-wave detected from the ECG data. HEPs were calculated by focusing on the 350–500 ms post-R-wave interval in the central and temporal regions. A paired t-test was performed to compare HEP amplitudes between the sitting and standing conditions.HEP amplitudes were significantly lower in the standing condition than those in the sitting condition [standing: mean ± SD = 0.43 ± 0.86 μV; sitting: 1.27 ± 1.16 μV; paired t-test: t (19) = 2.63, p = .016, d = .59] (Fig A and B). The decrease in HEP amplitudes during standing probably reflects suppressed interoceptive processing, attributed to a redistribution of attentional resources from internal to external sensory processing, necessary for postural control during standing.Posture may influence specific neurophysiological processes related to interoception.