Urethane-based adhesive composition

A urethane-based adhesive composition comprising:

• a urethane prepolymer;
• a carbon black A having a dibutyl phthalate oil absorption number of 30 to 40 ml/100 g;
• a carbon black B having a dibutyl phthalate oil absorption number of 98 to 108 ml/100 g;
• a calcium carbonate C;
• a plasticizer D;
• a modified product E of an aliphatic diisocyanate;
• and
• a catalyst,
• the urethane-based adhesive composition being configured to satisfy all of the following (1) to (6):
• 25≤a≤35 (1)
• 55≤b≤75 (2)
• 197≤a+3b≤251 (3)
• 32≤c<35 (4)
• 35≤d≤45 (5)
• 9≤e≤13 (6)
• where “a” in the (1) and (3) represents a content of the carbon black A with respect to 100 parts by mass of the urethane prepolymer,
• “b” in the (2) and (3) represents a content of the carbon black B with respect to 100 parts by mass of the urethane prepolymer,
• “c” in the (4) represents a content of the calcium carbonate C with respect to 100 parts by mass of the urethane prepolymer,
• “d” in the (5) represents a content of the plasticizer D with respect to 100 parts by mass of the urethane prepolymer,
• “e” in the (6) represents a content of the modified product E with respect to 100 parts by mass of the urethane prepolymer, and
• units of the “a” to “e” are parts by mass.