A PDA use antenna device comprising a first antenna for use in a first use configuration, a second antenna for use in a second use condition, a control part which discriminates between said first use condition and said second use condition and outputs a discrimination signal and a antenna selection device which selects which one of said first antenna and said second antenna should be used on the basis of the discrimination signal of said control part and connects the selected antenna to the wireless circuit. By selecting and using the optimal antenna for each use condition, use conditions can be easily discriminated. Moreover improved and stable antenna reliability can be ensured irrespective of use condition.