An information processing device comprising: a storage device having a program stored therein; and a hardware processor, wherein the hardware processor executes the program stored in the storage device to: acquire first data having a dimension of position related to an object represented in a generalized coordinate system, wherein the object is a human body, the object is defined as including a plurality of segments and at least one joint, configured to be rotatable around at least one axis, that links two or more of the segments, each of the plurality of segments is each area of the human body, and the generalized coordinate system includes at least one rotation angle around the at least one axis for the at least one joint as a variable; acquire at least second data having a dimension of acceleration from a plurality of inertial sensors attached to the plurality of segments and the at least one joint of the object; derive a transformation rule on the basis of the first data; convert the second data into third data having a dimension of acceleration represented in the generalized coordinate system by applying the transformation rule to the second data; and estimate at least one of a torque which is generated in the at least one joint and ground reaction forces acting on the object on the basis of the first data, fourth data having a dimension of speed relating to the object obtained by differentiating the first data, and the third data. a storage device having a program stored therein; and a hardware processor, wherein the hardware processor executes the program stored in the storage device to: acquire first data having a dimension of position related to an object represented in a generalized coordinate system, wherein the object is a human body, the object is defined as including a plurality of segments and at least one joint, configured to be rotatable around at least one axis, that links two or more of the segments, each of the plurality of segments is each area of the human body, and the generalized coordinate system includes at least one rotation angle around the at least one axis for the at least one joint as a variable; acquire at least second data having a dimension of acceleration from a plurality of inertial sensors attached to the plurality of segments and the at least one joint of the object; derive a transformation rule on the basis of the first data; convert the second data into third data having a dimension of acceleration represented in the generalized coordinate system by applying the transformation rule to the second data; and estimate at least one of a torque which is generated in the at least one joint and ground reaction forces acting on the object on the basis of the first data, fourth data having a dimension of speed relating to the object obtained by differentiating the first data, and the third data. acquire first data having a dimension of position related to an object represented in a generalized coordinate system, wherein the object is a human body, the object is defined as including a plurality of segments and at least one joint, configured to be rotatable around at least one axis, that links two or more of the segments, each of the plurality of segments is each area of the human body, and the generalized coordinate system includes at least one rotation angle around the at least one axis for the at least one joint as a variable; acquire at least second data having a dimension of acceleration from a plurality of inertial sensors attached to the plurality of segments and the at least one joint of the object; derive a transformation rule on the basis of the first data; convert the second data into third data having a dimension of acceleration represented in the generalized coordinate system by applying the transformation rule to the second data; and estimate at least one of a torque which is generated in the at least one joint and ground reaction forces acting on the object on the basis of the first data, fourth data having a dimension of speed relating to the object obtained by differentiating the first data, and the third data.