PURPOSE: To obtain a sealant having an excellent crack resistance and useful for electronic and electrical parts, by comprising a liquid epoxy compd, a specific copolymer, a liquid acid anhydride as a curing agent, fine particles of spherical inorganic filler, a silane coupling agent and a curing accelerator in a specified ratio.

CONSTITUTION: The objective sealant comprises (A) 100pts.(wt.) of a liquid epoxy compd. having ≥2 epoxy groups in the molecule, (B) 10W60pts. of a liquid butadiene-acrylonitrile copolymer having COOH groups at the molecular terminals (preferably one having a mol.wt. of 2,000W6,000 and contg. 5W30wt% acrylonitrile), (C) 0.8W1.2 equivs. (per epoxy group) of a liquid acid anhydride as a curing agent (e.g., methylhexahydrophthalic anhydride), (D) 15W65vol% (based on the total vol.) of a particulate inorganic filler with an average particle size of 1W10μ, (E) 0.5W5pts. of a silane coupling agent and (F) 0.3W3pts. of a curing accelerator.