Resin composition, prepreg, metal foil-clad laminate and printed circuit board

A resin composition comprising hollow particles and a matrix resin,

• wherein the hollow particles comprise a shell, which contains a resin, and a hollow portion surrounded by the shell;
• the hollow particles have a void ratio of 50% or more;
• the hollow particles have at least one kind of reactive group selected from the group consisting of an acidic group and an amino group on a surface thereof;
• and the hollow particles satisfy at least one selected from the group consisting of the following [a] and [b]:
• [a] an acidic group amount per unit area, which is obtained from an acid value of the hollow particles and a specific surface area thereof by the following formula (A), is 0.50 μmol/m2 or more
• Acidic group amount(μmol/m2)=Acid value(μmol/g)/Specific surface area(m2/g) Formula (A)
• [b] an amino group amount per unit area, which is obtained from an amine value of the hollow particles and a specific surface area thereof by the following formula (B), is 5.0 μmol/m2 or more
• Amino group amount(μmol/m2)=Amine value(μmol/g)/Specific surface area(m2/g) Formula (B), and
• wherein the matrix resin comprises a matrix resin containing a functional group which is reactive with the reactive group of the hollow particles.