We found that the crystallization of TIPS pentacene thin film plays an important role in determining the electrical property of organic thin film transistor (OTFT). OTFTs were fabricated using two different TIPS pentacenes, namely big grains and dendrite grains. Poly-4-vinylphenol (PVP) was used as a gate insulator, and Au electrode was evaporated using a shadow mask. The channel lengths of OTFTs with the bottom gate structure were 20-40 um.The mobility values of OTFTs fabricated with big grains reveal ten time higher values than those obtained from OTFTs fabricated with dendrite grains. The physical properties of the TIPS pentacene films were analyzed using optical microscope (OM), x-ray diffraction (XRD) and secondary electron microscopy (SEM). The electric characteristics of OTFT were obtained using Keithley-4200.OTFT utilizing ink jet print process has been attracted for the application such as bar code, low function flexible display, and electronic paper due to the advantage in the low end function electronics with low cost and easy fabrication. (1-2) There are various print processes such as Inkjet, Flexography, Gravure, Offset and Screen printing in printing process. Among them, inkjet-printing attracts much attention in device fabrication due to its many advantages including non-contact patterning, good local registration, low material waste thereby enabling to fabricate flexible and light-weight electronic products based on OTFT.The pentacene material should be chemically synthesized to be soluable in a certain solvent thereby enabling to print on the surface as a droplet. (3) The TIPS pentacene film would be formed by evaporating the solvent at the droplet surface. The degree of crystallization or crystalline morphology strongly depends on either the wettability of the solution on the surface or the evaporation rate at the droplet surface. The well coffeestain effect is arisen due to the evaporation difference between the peripheral edge and the center region. (4-6) Due to the aforementioned effect the mobility values reported from previous studies are below 0.01 cm 2 /Vs. (7-9) Such values are related with the crystallization through the carrier scattering phenomenon. The mobility value obtained from TIPS pentacene dissolved by the solvent having lower boiling point is about 0.00066 cm 2 /Vs, while that obtained from TIPS pentacene dissolved by the solvent having higher boiling point appears about 0.01 cm 2 /Vs. (10) According to the studies about the crystalline morphology with respect to the solvent, the TIPS pentacene films are typically composed with two different types of grains