: Aerodynamic interaction between a side-jet from a blunt body and its external flowfield was experimentally investigated. Experiments were conducted at the shock tunnel of Nagoya University with a Mach number of 8.1. The model used in this study is a 10• half-angle blunted cone, where a circular sonic air jet is injected at right angles to the body surface on the leeward side. To investigate the flowfield and the effects of attack angle on interaction, detailed surface pressure measurements were performed as well as visualizations. As attack angle increases from 0 to 40 deg, the region with aerodynamic interaction extends upstream from the nozzle. The magnitude of pressure changes due to the interaction decreases with attack angle, whereas the interaction amplification factor increases. Furthermore, a relatively large flow oscillation with about 5 kHz, which was caused by the aerodynamic interaction, was observed, where a linear relation exists between Mach number and Strouhal number. Finally, a simple empirical model to show a characteristic of shock-wave-induced aerodynamic interaction is proposed here, which shows good agreement with experimental data.