Spark plug

A spark plug comprising a center electrode and a ground electrode,

• at least one electrode of the center electrode and the ground electrode including:
• an electrode base material;
• a noble metal tip having a discharge surface that forms a gap between the noble metal tip and the other electrode;
• an intermediate member that is disposed between the electrode base material and the noble metal tip, the intermediate member including a body portion located at the noble metal tip side and a flange portion having a larger diameter than the body portion and located at the electrode base material side;
• a first melt portion that is formed between the body portion of the intermediate member and the noble metal tip;
• and
• a second melt portion that is formed, between the flange portion of the intermediate member and the electrode base material, at least at a position of intersection with an axial line of the noble metal tip,
• wherein in a cross section including the axial line of the noble metal tip,
• when:
• a diameter of the noble metal tip is denoted by Tw;
• the shortest distance between the second melt portion and a boundary between the first melt portion and the intermediate member is denoted by S1;
• and
• the longest distance between the second melt portion and the boundary between the first melt portion and the intermediate member is denoted by S2,
• 1.0 mm≤Tw≤1.2 mm and (S2−S1)≤0.3 mm are met.