NOVELTY - A naphthalene derivatives (I) or (II) are new.    USE - Naphthalene derivatives are used for organic thin-film transistor, organic-semiconductor material, organic thin-film transistor material, coating solution, organic-semiconductor thin film (all claimed), organic thin film solar cell, photoelectric conversion material, solid-state image sensor and nonluminous organic transistor.    ADVANTAGE - The naphthalene derivative provides organic thin-film transistor having high carrier mobility and favorable solubility.    DETAILED DESCRIPTION - A naphthalene derivatives of formula (I) or (II) are new.    X=S or O;    R1-R4=H or substituents having length of 3.7 Angstrom or less;    R5=H, alkyl, alkenyl, alkynyl, alkylthio, alkoxy, or aryl or heteroaryl (both optionally substituted by alkyl, alkenyl, alkynyl, alkoxy, alkylthio, acyl or silyl)(excluding group of formula: La-Ra);    La=divalent coupling group of formula (i)-(xii);    Ra=oligooxyethylene having v number of oxyethylene units, oligosiloxane having 2 or more silicon atoms, or alkyl or trialkylsilyl (both optionally substituted);    Lb,Lc=La;    Rb,Rc=Ra;    m=0-4;    m'=0-2;    R'=H or optionally substituted 1C or more alkyl;and    Y"=1C or more alkyl, 2C or more alkenyl, 2C or more alkynyl or 1C or more alkoxy (all optionally substituted).    (i) When Ra-Rc is optionally substituted alkyl, then group of La-Lc is 3 or more carbon atoms, group (ii) and (iii) of La-Lc are 2 or more carbon atoms and group (iv)-(xii) of La-Lc are 4 or more carbon atoms; and (ii) When Ra-Rc is optionally substituted trialkylsilyl, then La adjacent to Ra is group (iii). INDEPENDENT CLAIMS are included for the following:    (1) organic thin-film transistor, which contains semiconductor active layer containing naphthalene derivatives (I) or (II);    (2) organic-semiconductor material, which contains naphthalene derivatives (I) or (II);    (3) organic thin-film transistor material;    (4) coating solution; and    (5) organic-semiconductor thin film.