A failure detection device for a gas turbine engine of an aircraft comprising: an input module that receives values measured by a plurality of sensors that are failure detection targets; an accumulated data storage unit that stores a plurality of sensor values that were acquired in past as accumulated data; a unit space generating module that extracts sensor values of a unit space that are used in an MT system, namely Mahalanobis-Taguchi system, from the accumulated data storage unit, for extracted sensor values, uses values as they are for condition sensor values defined as sensor values that affect other sensor values and sensor values that are not affected by the condition sensor values, uses values nondimensionalized by the condition sensor values or values adjusted by the condition sensor values for the other sensor values affected by the condition sensor values, and thereby generates a unit space; a signal space generating module that, upon inputting a plurality of sensor values that are the failure detection targets to the input module, uses values as they are for the condition sensor values and the sensor values that are not affected by the condition sensor values, uses values nondimensionalized by the condition sensor values or values adjusted by the condition sensor values for the other sensor values, and thereby generates a signal space that is an aggregate of diagnosis data that are used in the MT system; and a determining module that compares a distance that represents a relationship between the unit space generated by the unit space generating module and the signal space generated by the signal space generating module with a predetermined threshold value, and determines presence/absence of a possibility of a failure of any of the sensors. an input module that receives values measured by a plurality of sensors that are failure detection targets; an accumulated data storage unit that stores a plurality of sensor values that were acquired in past as accumulated data; a unit space generating module that extracts sensor values of a unit space that are used in an MT system, namely Mahalanobis-Taguchi system, from the accumulated data storage unit, for extracted sensor values, uses values as they are for condition sensor values defined as sensor values that affect other sensor values and sensor values that are not affected by the condition sensor values, uses values nondimensionalized by the condition sensor values or values adjusted by the condition sensor values for the other sensor values affected by the condition sensor values, and thereby generates a unit space; a signal space generating module that, upon inputting a plurality of sensor values that are the failure detection targets to the input module, uses values as they are for the condition sensor values and the sensor values that are not affected by the condition sensor values, uses values nondimensionalized by the condition sensor values or values adjusted by the condition sensor values for the other sensor values, and thereby generates a signal space that is an aggregate of diagnosis data that are used in the MT system; and a determining module that compares a distance that represents a relationship between the unit space generated by the unit space generating module and the signal space generated by the signal space generating module with a predetermined threshold value, and determines presence/absence of a possibility of a failure of any of the sensors.