Latex for friction material, and friction material

Provided is a latex for a friction material containing rubber particles that comprise carboxyl-group-containing highly saturated nitrile rubber containing α,β-ethylenic unsaturated nitrile monomer units in a proportion of 10-60 wt% and having an iodine value of 120 or less, wherein the latex for a friction material is characterized in that the difference Δd(Δd = d90 - d50) between the 90% volume-cumulative particle diameter (d90) and the 50% volume-cumulative particle diameter (d50) of the rubber particles, as measured by a light-scattering method, is 0.0240 μm or greater.