According to one embodiment of the present disclosure, a motor monitoring device that can easily ascertain the state of a motor comprises a rotational speed acquisition unit that acquires the rotational speed of a motor that operates in accordance with an operation program, an output value acquisition unit that acquires an output value for the motor, and a graph display unit that plots a marker that represents a combination of the rotational speed and the output value at a graph area where one axis is the rotational speed and the other axis is the output value. The graph display unit has a unit area setting unit that sets a plurality of unit areas that divide the graph area into a grid and a format modification unit that modifies the display format of the marker by unit area in accordance with a prescribed indicator.

A diagnostic device includes a reception unit and a determination unit. The reception unit is configured to receive context information and sensing information. The context information corresponds to a certain operation of a target item that constitutes a target device. The context information is a piece of a plurality of pieces of context information each describing an operation of the target item determined depending on a type of operation of the target device. The sensing information is on a physical quantity that varies in accordance with the operation of the target item. The determination unit is configured to determine a state of the target item based on the sensing information detected while the target item is performing the certain operation, and based on a model corresponding to the received context information. The model is a model of one or more models respectively defined for one or more pieces of the context information.