This is a posable action figure from the Nendoroid series.
From the Good Smile Company website:
Hatsune Miku is joining the "Nendoroid Co-de" brand of figures! She has been sculpted wearing the "Ha2ne Miku" module that was seen in SEGA feat. HATSUNE MIKU Project's "Hatsune Miku -Project DIVA-" promotional video! Various other modules from the series are also in production, so look forward to coordinating your very own outfits for Miku!