We designed and developed propeller-type 3,5,8-trithienyl-BODIPY dyesST-1,ST-2, andST-3, which have the same three units of tetramethyl-2-(thiophen-2-yl)-1,3-dioxolane, thiophene-2-carbaldehyde, or 2-(pyridin-4-yl)-3-(thiophen-2-yl)acrylonitrile at the 3-, 5-, and 8-positions on the BODIPY skeleton, respectively. In order to get an insight into the impacts of 3,5,8-trithienyl substituents on the BODIPY core on the optical and electrochemical properties, we performed the photoabsorption and fluorescence spectroscopy, Lippert-Mataga plots, cyclic voltammetry (CV) and density functional theory (DFT) calculations forST-1,ST-2, andST-3. The photoabsorption and fluorescence maxima (lambda absmax and lambda flmax) of the three 3,5,8-trithienyl-DODIPY dyes exhibit bathochromic shifts in the order ofST-1(ca.640 and 660 nm) <ST-2(ca.660 and 680 nm) <ST-3(ca.730 and 750 nm), which appear in significantly longer wavelength regions compared to those of the 3,5,8-triphenyl BODIPY dye. This fact indicates that the expansion of the pi-conjugated system by the introduction of thiophene units as spacers at the 3-, 5-, and 8-positions onto the BODIPY core can lead to bathochromic shifts of photoabsorption and fluorescence bands to the red/NIR region. It was found that the photoabsorption and fluorescence bands of the propeller-type 3,5,8-trithienyl-BODIPY dyes are nearly independent of solvent polarity, that is,ST-1,ST-2, andST-3show feeble solvatochromic properties. Moreover, we revealed thatST-3possesses the ability to generate singlet oxygen (O-1(2)) under visible light irradiation, and thus, this result provides useful knowledge in molecular design of efficient BODIPY-based photosensitizers for photodynamic therapy (PDT).