An object of the invention is a method for measuring pressure under a flexi- ble cover (202) by utilizing electromagnetic waves. In the method is directed laser radiation to the cover (202) from a distance (200) to generate vibration or mechanical wave to the cover (202) at at least one generation location (204) in the cover on the basis of photoacoustic phenomena, and the gener- ation location being at least one point (204) where the laser radiation hits the cover (202). In the method is detected on the basis of electromagnetic waves cover vibrations due to the mechanical wave, and is recorded the de- tected mechanical wave at at least one recording location (206) to form me- chanical wave information. In the method is determined pressure information of pressure under the flexible cover (202) based on at least one recorded signal.
