A tunnel excavation device includes a front body section and a rear body section. The front body section includes a cutter head, a cutter head support, peripheral plates, a roof shoe, and side shoes. The cutter head includes a plurality of roller cutters. The cutter head support supports the cutter head. The peripheral plates, the roof shoe, and the side shoes are provided to the outer circumference and can be collapsed inward. The rear body section is disposed to the rear of the front body section. The rear body section includes a gripper section. The gripper section obtains a reaction force for performing excavation.