The purpose is to provide an immunity-inducing agent which can be implanted or injected in vivo by a simple operation and is capable of activating the in vivo immunological actions without causing adverse side effects. An immunity-inducing agent comprising β-tricalcium phosphate (β-TCP) having a porosity of 50% or less is implanted or injected in vivo, particularly in the vicinity of a lesion area (non-lesion area) such as cancer. Lymphocytes such as T cells, B cells and NK cells or a dendritic cell can be induced in the vicinity of β-TCP, and a lymphadenoid tissue is formed in which lymphocytes are localized at a high density. Examples of the dosage form of the immunity-inducing agent include particles or granules having a particle or grain size of equal to or greater than 0.05 μm and less than 25 μm, as well as tablets or columellas.
