NOVELTY - A thermoelectric conversion element (1) comprises electrode (13), thermoelectric conversion layer (14), and electrode (15), on base material (12). The thermoelectric conversion layer contains nano electroconductivity material and polymer including phenylene vinylene structure (I) as repeating structure.    USE - Thermoelectric conversion element is used for articles for thermoelectric generations, and power supply for sensors (all claimed). Uses include but are not limited to hot spring heat generator, solar thermal power generation machine, waste-heat generator, wristwatches, film for thermoelectric generation, and power supply for remote districts and space.    ADVANTAGE - The thermoelectric conversion element has excellent thermoelectric conversion performance index and favorable aging stability even at high temperature and humidity, with long-term durability.    DETAILED DESCRIPTION - A thermoelectric conversion element comprises electrode (13), thermoelectric conversion layer, and electrode (15), on base material. The thermoelectric conversion layer contains nano electroconductivity material and polymer including phenylene vinylene structure of formula (I) as repeating structure.    R1,R4,R5=aryl, heteroaryl, aliphatic heteroaryl, alkyl or alkoxy;    R2,R3=H, aryl, heteroaryl, aliphatic heterocyclyl, alkyl or alkoxy;    X1=single bond, aryl, heteroaryl, -BR11-, -NR11-, or group of formula: X2-C(R4)=C(R5)- (1A);    X2=single bond, aryl, heteroaryl, -BR11-, -NR11-;    R11=monovalent organic group;    n=1-4;and    m=1 or 2.    (i) When m is 1, X1 is not single bond; and (ii) When m is 1, group (1A) is different group from phenylene vinylene structure (I). An INDEPENDENT CLAIM is included for thermoelectric conversion material.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the thermoelectric conversion element.    Thermoelectric conversion element (1)    Metal plate (11)    Base material (12)    Electrodes (13,15)    Thermoelectric conversion layer (14)