  We investigate radioactivity from the decay sequence of 44Ti 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 initial 44Ti mass of (0.82-2.3) 10^{-4} solar mass within the
current uncertainty of the physical quantities. The resulting fluxes of gamma-
and hard X-rays emerged from the 44Ti 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 of 44Ti ionization on the estimated
fluxes is briefly remarked.
