To provide a new toothbrush for making bristle tips reach an interdental pat and a dental root, even if the toothbrush is lightly pressed on the teeth, enhancing removavility of bacterial plaques and gentle to teeth without damaging the enamel and the gums of the teeth.

Lateral directional bristle rows 2 are implanted almost close to a tooth width in a toothbrush head 1, and lateral directional bristle row spaces 3 are arranged to reduce resistance received from a projecting surface of the teeth. Bristles of the toothbrush easily reach the interdental part and the dental root, and can enhance removing capacity of the sticking bacterial plaques.