A cleaning tool, having a cleaning sheet and a holder for holding the cleaning sheet, wherein: the cleaning sheet is configured to extend in a longitudinal direction which is defined by a direction of insertion of the holder into the cleaning sheet, and in a transverse direction which is defined by a direction crossing the longitudinal direction, the holder has a holding part for holding the cleaning sheet, and a grip part which is connected to the holding part and designed to be held by a user, the cleaning sheet has a brush part capable of cleaning an object to be cleaned, a base, and an insertion part which is formed on the base and into which the holding part is inserted, the brush part includes a first brush part provided on one side of the base and a second brush part provided on the other side of the base, and the first brush part and the second brush part have a first region and a second region, respectively, which have different structures, wherein: the brush part comprises a fiber assembly, and the fiber assembly includes a first fiber assembly (100GF1) which forms the first brush part and a second fiber assembly (100GF2) which forms the second brush part, and the first fiber assembly (100GF1) and the second fiber assembly (100GF2) have different finenesses. the cleaning sheet is configured to extend in a longitudinal direction which is defined by a direction of insertion of the holder into the cleaning sheet, and in a transverse direction which is defined by a direction crossing the longitudinal direction, the holder has a holding part for holding the cleaning sheet, and a grip part which is connected to the holding part and designed to be held by a user, the cleaning sheet has a brush part capable of cleaning an object to be cleaned, a base, and an insertion part which is formed on the base and into which the holding part is inserted, the brush part includes a first brush part provided on one side of the base and a second brush part provided on the other side of the base, and the first brush part and the second brush part have a first region and a second region, respectively, which have different structures, wherein: the brush part comprises a fiber assembly, and the fiber assembly includes a first fiber assembly (100GF1) which forms the first brush part and a second fiber assembly (100GF2) which forms the second brush part, and the first fiber assembly (100GF1) and the second fiber assembly (100GF2) have different finenesses. the cleaning sheet has a brush part capable of cleaning an object to be cleaned, a base, and an insertion part which is formed on the base and into which the holding part is inserted, the brush part includes a first brush part provided on one side of the base and a second brush part provided on the other side of the base, and the first brush part and the second brush part have a first region and a second region, respectively, which have different structures, wherein: the brush part comprises a fiber assembly, and the fiber assembly includes a first fiber assembly (100GF1) which forms the first brush part and a second fiber assembly (100GF2) which forms the second brush part, and the first fiber assembly (100GF1) and the second fiber assembly (100GF2) have different finenesses. the brush part comprises a fiber assembly, and the fiber assembly includes a first fiber assembly (100GF1) which forms the first brush part and a second fiber assembly (100GF2) which forms the second brush part, and the first fiber assembly (100GF1) and the second fiber assembly (100GF2) have different finenesses.