NOVELTY - A thermoelectric conversion element (1) has electrode (13), thermoelectric conversion layer (14) and electrode (15) on base (12,16). The thermoelectric conversion layer contains nano electroconductive material and a polymer having nitrogen-containing repeating unit (I).    USE - Thermoelectric conversion element e.g. Peltier device is used for power supply for articles for thermoelectric generations e.g. sensor (all claimed). Uses include but are not limited to power supply for remote districts, space power supply, power supply for wrist watch, hot spring heat generator, solar thermal power generation machine, waste-heat generator and semiconductor drive power supply.    ADVANTAGE - The thermoelectric conversion element has excellent thermoelectric conversion performance such as thermoelectromotive force, and can maintain the performance with respect to thermocycle.    DETAILED DESCRIPTION - A thermoelectric conversion element has electrode (13), thermoelectric conversion layer and electrode (15) on base. The thermoelectric conversion layer contains nano electroconductive material and a polymer having nitrogen-containing repeating unit of formula (I).    Ar11,Ar12=arylene or heteroarylene;    Ar13=aryl or heteroaryl;    R11-R13=substituent;    or R11+R12,R11+R13,R12+R13=ring;    L=single bond or linking group of formula (l-1)-(l-4);    n11-n13=0-4;    n1=5 or more;    Ar14,Ar16=arylene or heteroarylene;    Ar15=aryl or heteroaryl;    R14-R16=substituent;    or R14+R12,R15+R12,R16+R12,R15+R16=ring;    n14-n16=0-4;    X1=arylene carbonyl arylene or arylene sulfonyl arylene;and    X2=arylenyl, heteroarylenyl or linking group which is formed by coupling arylenyl and heteroarylenyl.    An INDEPENDENT CLAIM is included for thermoelectric conversion material, which comprises polymer having nitrogen-containing repeating unit (I) for forming thermoelectric conversion layer of thermoelectric conversion element.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of thermoelectric conversion element.    Thermoelectric conversion element (1)    Metal plates (11,17)    Base (12,16)    Electrodes (13,15)    Thermoelectric conversion layer (14)