A feature extraction method for a feature extraction device, the method comprising: a step of forming a feature group (step #14) by grouping a cluster of features, each feature regarding a road marking and being stored in a predetermined feature information storage unit, and including information of the position of the road marking along a road and information of a feature attribute, the information of the feature attribute being information including information of a feature type representing a type of the road marking and information of a state of the road marking, the step being performed by a feature group formation unit of the feature extraction device, wherein in the step the features to be grouped are sequentially retrieved according to their position in a direction along a road starting from an initial feature of the group, and a feature is grouped together to other already grouped features, if its distance to one already grouped feature is less than or equal to a grouping interval so that, when another feature is not retrieved within the grouping interval, a new group is started; a step of excluding (step #15), which is performed by an exclusion unit of the feature extraction device, based on the feature type or the state of a feature, a feature not suitable for use in an image recognition process of the feature with respect to image information, from the feature group; and a step of extracting (step #18), which is performed by an extraction unit of the feature extraction device, a part or all of one or more of the features within the feature group remaining as a result of the excluding, as a target feature suitable for the use in the image recognition process. a step of forming a feature group (step #14) by grouping a cluster of features, each feature regarding a road marking and being stored in a predetermined feature information storage unit, and including information of the position of the road marking along a road and information of a feature attribute, the information of the feature attribute being information including information of a feature type representing a type of the road marking and information of a state of the road marking, the step being performed by a feature group formation unit of the feature extraction device, wherein in the step the features to be grouped are sequentially retrieved according to their position in a direction along a road starting from an initial feature of the group, and a feature is grouped together to other already grouped features, if its distance to one already grouped feature is less than or equal to a grouping interval so that, when another feature is not retrieved within the grouping interval, a new group is started; a step of excluding (step #15), which is performed by an exclusion unit of the feature extraction device, based on the feature type or the state of a feature, a feature not suitable for use in an image recognition process of the feature with respect to image information, from the feature group; and a step of extracting (step #18), which is performed by an extraction unit of the feature extraction device, a part or all of one or more of the features within the feature group remaining as a result of the excluding, as a target feature suitable for the use in the image recognition process.