A pet body fat measuring tool 10 for measuring pet body fat by measuring bioelectrical impedance including an electrode body 11 having at least two voltage electrodes 13 and at least two current electrodes 14 and being used by being pressed to a part of a pet body and a control calculating unit having an impedance measuring circuit connected to the electrode body 11 to control the current made to flow at a time of measurement and to calculate body fat based on bioelectrical impedance determined from measured voltages, wherein a distance L1 between each of the voltage electrodes and each of the current electrodes 14 of the electrode body and a distance L2 between the voltage electrodes 13 of the electrode body 11 are fixed. An electrolysis solution or organic solvent is held and supported by body hairs existing between a surface of a pet body and a surface of each of the electrodes 13, 14.