A wheel load estimation device that estimates a wheel load of a vehicle, the wheel load estimation device comprising: a wheel speed acquisition unit that acquires wheel speed information of each wheel (FL, FR, RL, RR) included in the vehicle, from a wheel speed sensor mounted on the vehicle; a frequency characteristic ratio calculation unit that calculates, based on the wheel speed information, a front-to-rear frequency characteristic ratio that changes with a change in a front-to-rear load ratio that is a ratio between a load exerted on a front wheel (FL, FR) of the vehicle and a load exerted on a rear wheel (RL, RR) of the vehicle, and characterised by the the frequency characteristic ratio calculation unit calculating also a left-to-right frequency characteristic ratio that changes with a change in a left-to-right load ratio that is a ratio between a load exerted on a left wheel (FL, RL) of the vehicle and a load exerted on a right wheel (FR, RR) of the vehicle; and by the estimation device further comprising a load ratio calculation unit that calculates the front-to-rear load ratio and the left-to-right load ratio based on the front-to-rear frequency characteristic ratio and the left-to-right frequency characteristic ratio, respectively; and by the estimation device further comprising a wheel load calculation unit that calculates a wheel load ratio representing a relative wheel load among the wheels (FL, FR, RL, RR) included in the vehicle, for at least one of the wheels (FL, FR, RL, RR) of the vehicle, based on the front-to-rear load ratio and the left-to-right load ratio, wherein the frequency characteristic ratio calculation unit calculates, as the front-to-rear frequency characteristic ratio, a front-to-rear gain ratio that is a ratio of a gain in a frequency spectrum of acceleration of a front wheel (FL, FR) with respect to a gain in a frequency spectrum of acceleration of a rear wheel (RL, RR) at two or more specific frequencies, and calculates, as the left-to-right frequency characteristic ratio, a left-to-right gain ratio that is a ratio of the gain in a frequency spectrum of acceleration of a left wheel (FL, RL) to the gain in a frequency spectrum of acceleration of a right wheel (FR, RR) at two or more specific frequencies; and the load ratio calculation unit calculates the front-to-rear load ratio by taking a linear combination of the calculated two or more front-to-rear gain ratios using weights that are different from one another, and calculates the left-to-right load ratio by taking a linear combination of the calculated two or more left-to-right gain ratios with weights that are different from one another. a wheel speed acquisition unit that acquires wheel speed information of each wheel (FL, FR, RL, RR) included in the vehicle, from a wheel speed sensor mounted on the vehicle; a frequency characteristic ratio calculation unit that calculates, based on the wheel speed information, a front-to-rear frequency characteristic ratio that changes with a change in a front-to-rear load ratio that is a ratio between a load exerted on a front wheel (FL, FR) of the vehicle and a load exerted on a rear wheel (RL, RR) of the vehicle, and characterised by the the frequency characteristic ratio calculation unit calculating also a left-to-right frequency characteristic ratio that changes with a change in a left-to-right load ratio that is a ratio between a load exerted on a left wheel (FL, RL) of the vehicle and a load exerted on a right wheel (FR, RR) of the vehicle; and by the estimation device further comprising a load ratio calculation unit that calculates the front-to-rear load ratio and the left-to-right load ratio based on the front-to-rear frequency characteristic ratio and the left-to-right frequency characteristic ratio, respectively; and by the estimation device further comprising a wheel load calculation unit that calculates a wheel load ratio representing a relative wheel load among the wheels (FL, FR, RL, RR) included in the vehicle, for at least one of the wheels (FL, FR, RL, RR) of the vehicle, based on the front-to-rear load ratio and the left-to-right load ratio, wherein the frequency characteristic ratio calculation unit calculates, as the front-to-rear frequency characteristic ratio, a front-to-rear gain ratio that is a ratio of a gain in a frequency spectrum of acceleration of a front wheel (FL, FR) with respect to a gain in a frequency spectrum of acceleration of a rear wheel (RL, RR) at two or more specific frequencies, and calculates, as the left-to-right frequency characteristic ratio, a left-to-right gain ratio that is a ratio of the gain in a frequency spectrum of acceleration of a left wheel (FL, RL) to the gain in a frequency spectrum of acceleration of a right wheel (FR, RR) at two or more specific frequencies; and the load ratio calculation unit calculates the front-to-rear load ratio by taking a linear combination of the calculated two or more front-to-rear gain ratios using weights that are different from one another, and calculates the left-to-right load ratio by taking a linear combination of the calculated two or more left-to-right gain ratios with weights that are different from one another.