The method is meant for the evaluating of the amount of micro and macro cracks in the pavement of a traffic lane, such as a road or street. The colder water beneath the pavement is under the load of heavy traffic pumped into the micro and macro cracks in the pavement and lowers the temperature of the pavement, so a large difference between the temperatures in different points on the pavement reveals a large amount of cracks. In the method, the examination span of the traffic lane is first selected. Thereafter the temperature T1 of the heavily loaded part of the pavement of the selected examination span and the temperature T2 of the lightly loaded part of the pavement of the same examination span are determined. A difference AT between the determined temperatures is calculated, which difference is compared to a reference value. If the difference is larger than the used reference value, the pavement lets through a significant amount of water. If the difference is smaller than the used reference value, the condition of the pavement is sufficiently good. The temperatures t r of the heavily loaded part of the pavement are measured at the wheel ruts and the temperatures t k of the lightly loaded part of the pavement are measured in the area outside the wheel ruts. The temperatures of the pavement are measured with an apparatus, which is placed in a vehicle travelling on the traffic lane. Alternatively the emissivity ε r of the heavily loaded part of the pavement and the emissivity ε k of the lightly loaded part of the pavement can be determined and the difference Δε can be compared to a reference value.