Provided is an alkylsilane laminate with which it is possible to obtain an organic semiconductor film having excellent semiconductor properties. Such a laminate can be useful for an organic thin-film transistor. The alkylsilane laminate comprises an underlayer (Sub) having hydroxyl groups at the surface and an alkylsilane thin film (AS) formed on this underlayer. The alkylsilane laminate is a laminate wherein the critical surface energy Ec of the alkylsilane thin film and the number of carbons (X) of the alkylsilane satisfies the following formula (1): Ec≦29.00−0.63x (mN/m) (1) Also provided is a thin-film transistor (10) having such an alkylsilane laminate (Sub, AS).