When designing blast-resistant concrete members that are subject to contact detonation, it is necessary to reduce the spall damage due to tensile stress waves reflected from the back sides of the members. In a previous study, the authors confirmed the good spall-reducing performance under contact detonation of slurry-infiltrated fiber concrete (SIFCON), which is manufactured by first placing fibers into an empty mold and then infiltrating them with grout. In this study, to obtain SIFCON with further improved spall reduction, experimental investigations were conducted regarding the effects of different fiber types on the blast resistance of SIFCON slabs against contact detonation. Five types of steel fibers and four types of synthetic fibers were employed as reinforcing fibers. The thickness of the SIFCON slabs was fixed at 80 mm, and contact detonation tests were conducted using two amounts of SEP explosives. All of the SIFCON samples investigated reduced the spall damage due to contact detonation more effectively than normal concrete and other conventional fiber reinforced cementitious composites. Furthermore, by using SIFCON with fine straight steel fibers, the spall-limit thickness of the slab could be reduced by 54% or more.