A brake pad state estimation device that estimates a brake pad state including at least one of a wear volume and a temperature (Te) of a brake pad of a vehicle, the brake pad state estimation device comprising: a processor; and a storage, wherein the processor is adapted to execute: an information acquisition process acquiring sensor detection information that includes a vehicle speed and a brake pressure (Pb) detected by a sensor installed on the vehicle; a brake pad state calculation process calculating the brake pad state based on the sensor detection information during braking of the vehicle; an information output process storing a result of calculation of the brake pad state in the storage and/or transmitting the result of calculation of the brake pad state to an outside of the vehicle; characterised by a processing frequency control that variably sets a processing frequency of at least one of the brake pad state calculation process and the information output process, and in the processing frequency control, the processor is further adapted to set the processing frequency in a case where the vehicle speed is lower to be lower than the processing frequency in a case where the vehicle speed is higher, or to set the processing frequency in a case where the brake pressure (Pb) is lower to be lower than the processing frequency in a case where the brake pressure (Pb) is higher. a processor; and a storage, wherein the processor is adapted to execute: an information acquisition process acquiring sensor detection information that includes a vehicle speed and a brake pressure (Pb) detected by a sensor installed on the vehicle; a brake pad state calculation process calculating the brake pad state based on the sensor detection information during braking of the vehicle; an information output process storing a result of calculation of the brake pad state in the storage and/or transmitting the result of calculation of the brake pad state to an outside of the vehicle; characterised by a processing frequency control that variably sets a processing frequency of at least one of the brake pad state calculation process and the information output process, and an information acquisition process acquiring sensor detection information that includes a vehicle speed and a brake pressure (Pb) detected by a sensor installed on the vehicle; a brake pad state calculation process calculating the brake pad state based on the sensor detection information during braking of the vehicle; an information output process storing a result of calculation of the brake pad state in the storage and/or transmitting the result of calculation of the brake pad state to an outside of the vehicle; characterised by a processing frequency control that variably sets a processing frequency of at least one of the brake pad state calculation process and the information output process, and in the processing frequency control, the processor is further adapted to set the processing frequency in a case where the vehicle speed is lower to be lower than the processing frequency in a case where the vehicle speed is higher, or to set the processing frequency in a case where the brake pressure (Pb) is lower to be lower than the processing frequency in a case where the brake pressure (Pb) is higher.