A first acquisition unit acquires first data on first malfunction of a robot. A second acquisition unit acquires second data on second malfunction of the robot. A first determination unit determines whether or not to store the first data in accordance with the first data. A second determination unit determines whether or not to store the second data in accordance with the second data. A memory stores the first data and the second data. A controller stores the first data in the memory at a first period when the first determination unit determines to store the first data. The controller further stores the second data in the memory at a second period longer than the first period, when the first determination unit determines not to store the first data and the second determination unit determines to store the second data.