We investigate radioactivity from the decay sequence of44Ti in a young supernova remnant SN 1987A. We perform Monte‐Carlo simulations of degradation of the nuclear lines to explain a late‐time bolometric luminosity which is estimated from optical and near‐infrared observation at 3600 days after the explosion. Assuming the distance to LMC in between 45.5 and 52.1 kpc, we have obtained the initial44Ti mass of (0.82 – 2.3) × 10−4M⊙within the current uncertainty of the physical quantities. The resulting fluxes of &ggr;‐ and hard X‐rays emerged from the44Ti decay are estimated and compared with the line sensitivity of the INTEGRAL/SPI on board and that of NeXT X‐ray satellite planned to be launched in 2010. The effect of44Ti ionization on the estimated fluxes is briefly remarked. © 2004 American Institute of Physics