TlGaS2 crystals belong to triple thallium chalcogenides with well-pronounced lamellar structure. Due to specificity of crystal structure these crystals have a strong anisotropy of physical properties. The authors of Ref. [1] report about a high sensitivity of TlGaS2 monocrystals in x-ray diapason at energies 25 - 50 keV. The dependence of the crystal conductivity on intensity of x-ray radiation dose has a power character. Raman scattering spectra for different geometries and them temperature dependences for temperatures 77 - 400 K were investigated in TlGaS2 crystals. The vibrational spectra of reflection in region 50 - 4000 cm-1 were investigated and the polar vibrational LO and TO modes and they main parameters were distinguished. The calculations of relative effective charges of anions and cations in E||a and E||b polarizations show a difference of its ionicity degree along axes a and b [2]. These materials were intensively investigated (see Ref. [2] therein).  The crystals grown by Bridgmann method have 2x1x1 cm size and easy split off. The optical measurements were carried out on computerized spectrometers MDR-2, SPECORD M40 and JASCO-670. The low-temperature spectra were measured on samples mounted on cold-finger of Helium optical cryogenic system LTS-22 C 330.  The structure of TlGaS2 is described by C2h6 space group according crystallographic data. The unit cell has eight formula units. The main motive of structure is formed by tetrahedral polyhedrons Ga4S10 consist of four tetrahedrons of GaS4. The structure TlGaS2 is pseudo-tetragonal since a = b = 10.31 Å, c = 15.16 Å and β = 99.7°. The narrow peak at 2.605 eV due to forming of direct exciton in Brillouin zone center is observed in region of edge absorption at temperature 1.8 K in E||c polarization. Since crystals TlGaS2 are cleft perpendicular to crystallographic axis c that absorption spectra are measured for two polarizations of light waves E||a and E||b. Absorption spectra of crystals TlGaS2 were measured in E||a and E||b polarizations at temperatures 9 - 300 K. The excitonic peaks are observed in both polarizations and shifted to higher energies. The temperature shift coefficient of exciton maxima β is equal to 2.4x10-4 eV/K and 3.5x10-4 eV/K in E||a and E||b polarizations, respectively. The value of absorption coefficient in excitonic peaks maxima corresponds to 4000 cm-1. The indirect transitions considerably situated at energies 2.3 - 2.5 eV are not observed by us in both absorption spectra and wavelength modulated transmission spectra. The interference was observed in wavelength modulated transmission spectra measured at temperature 14 K at energies E < 2.55 eV.  Ground and excited states of excitons were found out in reflection (R) and wavelength modulated reflection (ΔR/Δλ) spectra of E||a and E||b polarizations. The main parameters of B2u (series A) and B3u (series B) excitons and bands in k = 0 were determined. The optical reflection and wavelength modulated reflection spectra of TlGaS2 crystals in E||a and E||b polarizations at temperatures 14 K and 300 K were investigated. The features associated with direct electron transitions in actual points of Brillouin zone were revealed. The optical functions (n, k, ε1 and ε2) indicating about anisotropy of optical parameters and electron transitions for wide energy diapason (2 - 6 eV) were calculated by Kramers-Kronig method from measured optical reflection spectra. Crystals TlGaS2 deposed between crossed polarizers are isotropic near wavelengths 493 nm (300 K) and 483 nm (14 K). Refractive indices for E||a and E||b polarizations intersect at these wavelengths. The refractive indices intersection was observed and for intrinsic absorption region.