According to an embodiment of the present disclosure, provided is a method for a first device to perform sidelink communication. The method may include the steps of: determining sidelink transmission power, for transmission to a second device, as first transmission power on the basis of an OLPC parameter and at least one parameter pertaining to SL PL; transmitting a first PSCCH or a first PSSCH to the second device on the basis of the first transmission power; determining the sidelink transmission power as second transmission power on the basis of a transmission power control operation for the first transmission power being triggered; and transmitting a second PSCCH or a second PSSCH to the second device on the basis of the second transmission power.