An electronic radial ultrasonic probe comprising an electronic radial array which comprises a plurality of ultrasonic transducers being continuously arrayed circularly around an insertion axis as center and also for which a transmission/reception of an ultrasonic wave is controlled by electronically selecting the plurality of ultrasonic transducer, comprises: a support member equipped on the electronic radial array; a lock member featured with a cavity in which the support member is inserted and with a lock groove for locking a balloon which is mounted in a manner to cover the electronic radial array and in which an ultrasonic medium is filled; and a filler member which is constituted by an adhesive material converting from a fluid state to a solid state, and is filled in the cavity.