Prepreg, metal-clad laminate, printed wiring board, and method for producing prepreg

A prepreg comprising:

• a first resin layer;
• and
• a second resin layer disposed on each of opposite faces of the first resin layer,
• wherein
• the first resin layer is a half-cured product of a first thermosetting resin composition that includes a glass cloth impregnated with the first thermosetting resin composition and contains no hexagonal boron nitride,
• the second resin layer is a half-cured product of a second thermosetting resin composition containing hexagonal boron nitride,
• the glass cloth has a warp and weft weave density of 54 pieces/25 mm or more,
• the hexagonal boron nitride has an average particle size ranging from 10 μm to 30 μm, and
• the hexagonal boron nitride is contained in an amount ranging from 20 parts by mass to 40 parts by mass relative to 100 parts by mass of a residual component other than the hexagonal boron nitride in the second thermosetting resin composition.