NOVELTY - A nano-crystal diamond film (2) comprises a nano-crystal diamond of crystal grain diameter of 1-1000 nm synthesized on a substrate (1), where the nano-crystal diamond film has a surface flatness of 2.1 nm or less.    USE - For an electrochemical component, such as an electrochemical electrode, DNA chip, organic electroluminescent element, organic electric field light receiving element, organic thin film transistor, cold electron emitting element, fuel cell, and metal carrying nano-crystal diamond catalyst (all claimed).    ADVANTAGE - The nano-crystal diamond film has excellent chemical stability and provides an electrochemical component with excellent chemical resistance, corrosion resistance and reliability.    DETAILED DESCRIPTION - A nano-crystal diamond film (2) comprises a nano-crystal diamond of crystal grain diameter of 1-1000 nm synthesized on a substrate (1), where the nano-crystal diamond film has a surface flatness of 2.1 nm or less. The nano-crystal diamond film contains sulfur, boron, oxygen, phosphorus, nitrogen and/or silica as impurity. The substrate is silicon, quartz, ceramic, metal, glass and/or polymeric substrate.    INDEPENDENT CLAIMS are also included for the following:    (1) an electrochemical component;    (2) an electrochemical electrode;    (3) a DNA chip;    (4) an organic electroluminescent element;    (5) an organic electric field light receiving element;    (6) an organic thin film transistor;    (7) a cold electron emitting element;    (8) a fuel cell;    (9) a metal carrying nano-crystal diamond catalyst;    (10) manufacturing a nano-crystal diamond film;    (11) manufacturing an electrochemical component;    (12) manufacturing an electrochemical electrode;    (13) manufacturing a DNA chip;    (14) manufacturing an organic thin film transistor;    (15) manufacturing a cold electron emitting element;    (16) manufacturing a fuel cell;    (17) manufacturing a metal carrying nano-crystal diamond catalyst;    (18) manufacturing an organic electroluminescent element; and    (19) manufacturing an organic electric-field light receiving element.    DESCRIPTION OF DRAWING(S) - The figure shows the sectional drawing of the nano-crystal diamond film.    substrate (1)    nano-crystal diamond film (2)