The values of the coefficient of friction in a single ball–plane contact have been measured experimentally under small normal loads (0.5–5 mN). The contact parts are made of steel. The experiments have been carried out in the absence of specially applied films on the contact surfaces and with thin fatty acid films layered on a flat contact part. The parameters of the specific force of friction τ0 and β have been obtained based on the work of I.V. Kragelskii. It has been proved that the adhesive interaction of contacting bodies and the subroughness of contacting surfaces must be taken into account in case of contact under small loads without fatty acid films. Experimentally obtained values of the specific force of friction are higher than the equivalent values known from literature and obtained in experiments at a macroscale level.