Currently, 2-thumb encircling technique is recommended in 2-rescuer infant cardiopulmonary resuscitation (CPR). However, many complications can occur during CPR. Therefore, we developed a novel compression assist device (Reheart) that can reduce chest compression area and determined whether using our device provides better compression quality. A novel compression assist device consists of 2 parts. The upper part was designed to put 2 thumbs together in the thumb sleeves, and the lower part was designed based on a circular rubber plate with a 2.0-cm diameter to confine compression area. Infant manikin CPR simulations using the 2-thumb encircling technique with Reheart and without Reheart were sequentially performed by participants in randomized crossover fashion. A total of 32 health care providers were included. The average age of the participants was 30.2 ± 3.5 years, and 21 participants (65.6%) were male. The accuracy in the Reheart group was better than that in the conventional group (proportion of compression on target area, 52.5% ± 13.2% vs 35.4% ± 17.6%; P < 0.001). The difference in the rates of chest compressions between the 2 groups was not significant (119.6 ± 14.4 vs 120.7 ± 14.0 compressions/min, P = 0.59). The depth of chest compressions was also not significantly different between the 2 groups (34.5 mm [33.6-34.9 mm] vs 34.2 mm [33.0-34.9 mm], P = 0.32). Our new compression assist device can help provide safe and effective chest compressions during 2-rescuer infant CPR.