Structures of excited states in 11 C and 11 B were studied based on variational calculations after spin-parity projection in a framework of antisymmetrized molecular dynamics (AMD). The calculations systematically reproduce experimental data of the transition strengths such as Gamov-Teller(GT) and M1 transitions. A well-developed cluster structure of 2α+3 He (t) was found in the [Formula: see text] state of 11 C (11 B ). We assigned this state to the observed [Formula: see text] state at 8 MeV. The calculations reproduce the small [Formula: see text] which has been measured in the recent experiments. It was found that the [Formula: see text] state has a dilute cluster state, and its features are similar to those of the [Formula: see text] which is considered to be a gas state of three α clusters.