The difference between abundances of such elements as Li, Be, B in active regions on the Sun and in the undisturbed atmosphere, if it exists at all, could be considered a very important indication on the possible nuclear reaction in active regions and on the rate of diffusion of elements inside magnetic fields of sunspots. One of the authors from the considerations of λ6707 Å has an estimated (Dubov, 1955) Li abundance in the undisturbed solar atmosphere as log N(Li) = 0·93 (taking log N(H) = 12·0), which is close to the later results (Goldberg et al., 1960). In sunspots we can expect that the first doublet λ6103 of Li diffuse series appears. The preliminary consideration (Dubov, 1964) showed that Li abundance in sunspots could be several times larger than the above estimate for the undisturbed atmosphere. This result forced us to consider as carefully as possible the region of λ6103 in eight spectra of four sunspots taken with the aid of the echelle-grating spectrograph of the Crimean observatory with a dispersion of 1 Å/mm and measured resolving power 0·03 Å. The consideration of the Zeeman pattern of this line shows that at the field strengths we had in sunspots (2000–3000 gs) the line should be diffuse band with width ~0·23 Å, and taking into account the broadening of the line the halfwidth of the line has not to be smaller than 0·25 Å.