Time-resolved fluorescence spectra of photosystem I (PS-I) trimeric complex isolated from a thermophilic cyanobacterium, Thermosynechococcus (T.) elongatus, were observed at 15 K over the time range from 100 fs to a few nanoseconds under P700-oxidized condition and 10 ps to a few nanoseconds under P700-reduced condition. Global-fitting analysis of the data of P700-oxidized condition revealed the existence of three kinetically different red chlorophylls (Chls) having the energy-transfer times to P700(+) of 6.1 ps (C-6.1 (ps)), 140 PS (C-140 (ps)), and 360 ps (C-360 (ps)). According to the spectral shape of DAS, C-6.1 (ps), C-140 (ps), and C-360 (ps) were assigned to the previously reported red Chls with the absorption maxima at 715 nm (C715), 710 nm (C710), and 719 nm (C719), respectively. In PS-I containing P700(+), ca. 60 Chls funnel the excitation energy into C-6.1 ps in a subpicosecond time region at 15 K. The analysis of the present data together with the conclusions of the previous reports revealed that in PS-I containing a neutral P700 the direct energy transfer from the bulk Chls to P700 seems to dominate the energy-flow process. Simulation of the energy-transfer time to P700(+) based on Forster theory suggested the dimeric Chls A32-B7 and A33-A34 as the most probable candidates for C-140 (ps) (C710) and C-360 (ps) (C719), respectively. C-6.1 (ps) (C715) was tentatively assigned to the dimeric Chl B24-B25 or A26-A27, for which the fastest energy transfer to P700(+) was predicted from the simulation. However, the estimated energy-transfer times to P700+ for these dimeric Chls were 44-46 ps, which were Still much slower than the observed value of 6.1 ps. A theoretical framework beyond the standard Forster theory might be required in order to account for the severe deviation.