In reacent years, studies on reducing the diameter of microcapsules for practical application to self-healing FRP have been conducted. This study clarifies how filler grain diameter and strength and filler volume fraction affect the interlaminar fracture toughness of FRP. The reinforcement material used in this experiment was carbon fiber fabric sheets. Acrylic particles were used as filler; the mechanical properties were similar to those of microcapsules of self-healing FRP. The filler volume fraction was confirmed to affect the interlaminar fracture toughness. The grain diameters of the hollow particles were smaller, and the Young's modulus of the filler is larger, confirming that the interlaminar fracture toughness increased. High rigidity and small-grain diameter microcapsules are considered to be appropriate microcapsules (enclosing repair agents) for self-healing of CFRP.