There are is a planar transformer and a method of manufacturing the same that can prevent resin being coated from being separated from a conductor during the manufacturing of a transformer by forming a dummy pattern on a board. A planar transformer according to an aspect of the invention may include: a core part having a pair of cores electromagnetically coupled to each other; a board part having a plurality of boards disposed between the pair of cores and stacked upon one another; a pattern part having a power transmission pattern provided on at least one board of the plurality of boards of the board part and transmitting power being input, and a dummy pattern provided on the same board having the power transmission pattern thereon and separated from the power transmission pattern by a predetermined interval; and a resin part being coated over the at least one board of the plurality of boards, the at least one board having the pattern part thereon.