Disclosed is a base station apparatus in which a configuration section (102) configures, within a data assignable region for a terminal apparatus (200), a first search space and a second search space each being a candidate to which control information is assigned, each of the first search space and the second search space including a plurality of control channel elements, and a signal assignment section (105) assigns control information to each of the first search space and the second search space. In addition, the configuration section (102) allocates numbers to a plurality of first control channel elements included in the first search space in an ascending order, and allocates numbers larger than or identical with the numbers allocated to the first control channel elements to a plurality of second control channel elements included in the second search space.