Spark plug voltage probe for use with an internal combustion engine

A spark plug voltage probe which detects a voltage applied to a spark plug installed in an internal combustion engine so as to analyze a burning condition in the internal combustion engine on the basis of the voltage applied to the spark plug, the spark plug voltage probe comprising:

• an insulator base (101) secured to the top of the internal combustion engine, an upper surface (111) of the insulator base (101) having a groove (112) in which a spark plug cable (105) is located and a lower surface (113) of the insulator base (101) having a cavity (114) as an accommodation space (115) in which electrical circuits are placed in a package substrate (103) by means of a resin filler (104);
• and
• an electrode plate (102) embedded in the insulator base (101) along the groove (112) and electrically connected to the electrical circuits by way of a lead wire (122).