In a control device of an internal-combustion engine according to the disclosure, an intake throttle valve (25) for adjusting an EGR valve differential pressure (ΔPEGR) is provided, an EGR valve upstream pressure (PEGR0) is estimated by using a target fresh air amount (GAIRCMD) (step 6), a target differential pressure (ΔPEGRCMD) is set to a smaller value as the target fresh air amount (GAIRCMD) becomes smaller (FIG. 5), and a difference between the EGR valve upstream pressure (PEGR0) and the target differential pressure (ΔPEGRCMD) is set as a target valve downstream pressure (P1CMD) (step 7). By using the target fresh air amount (GAIRCMD), the EGR valve upstream pressure (PEGR0), and the target valve downstream pressure (P1CMD), the target EGR valve opening degree (LEGRCMD) is set (step 23), and an EGR valve (43) is controlled based on the target EGR valve opening degree (step 24).