Silica-calcium phosphate nanocomposite (SCPC) is a porous bioactive resorbable bioactive ceramics. Incorporating apatite bone cement (AC) formulation of tetracalcium phosphate-dicalcium phosphate dihydrate and SCPC has contributed to the higher mechanical strength of a new prototype apatite cement formulation. This in-vitro experiment aims to investigate the bioactivity of AC formulation using simulated body fluid (SBF). The samples consist of two groups of AC formulations (n=4). The first group, AC with 10% SCPC and the second group AC without SCPC, was immersed in the SBF for 14 days. The samples before and after immersion were analyzed by X-Ray Diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDS), and Scanning Electron Microscope (SEM). The samples' size and degree of crystallinity were analyzed statistically using Shapiro-Wilk, Levene, and Mann-Whitney test. As a result, there was no significant difference in the crystal size and the degree of the crystallinity of both samples. The surface morphology of all samples were coated with hydroxyapatite after immersing in the SBF solution. Both AC formulations with and without SCPC have bioactivity as the bone substitute materials. Combining AC with SCPC50 is a promising method to improve the bioactivity and mechanical strength of calcium phosphate bone cement.