1.  Select from the top menu bar:  ツール(T) → マクロ(M) → セキュリティ(S).

2.  Change your setting to 中(M).  Click OK and close Excel.

3.  Open the file containing macros.  When prompted with a Security Warning, click マクロを有効にする(E).

Note:  In the future, you will only have to repeat step 3.