We summarize the review talk of ``Maser astrometry'' which was given in the 15th EVN (European VLBI Network) Symposium. The basics of VLBI astrometry is introduced in section 1. In section 2, we briefly introduce the background and context of the contributed talks given in the session ``Techniques 1''. In section 3, we review scientific achievements with maser astrometry, which are (1) the Galactic structure and (2) an accretion event in the high-mass protostar G358.93$-$0.03-MM1. The VLBA BeSSeL and VERA projects have compiled more than 200 VLBI astrometric results, which reveals that the Milky Way is a barred spiral with four major arms and secondary arms. The results update Galactic constants to be ($R_{0}$, $\Theta_{0}$) = (8.15$\pm$0.15 kpc, 236$\pm$7 km s$^{-1}$). The rotation velocity of the LSR, $\Theta_{0}$, is larger than the IAU 1985 recommendation value (i.e., 220 km s$^{-1}$). It indicates that the Milky Way is $\sim$10-30$\%$ heavier than previously thought, since the total mass of the Milky Way scales as $(\Theta_{0})^{3}$ in the NFW dark halo potential. The ``episodic accretion'' theory of high-mass star formation was observationally confirmed for G358.93$-$0.03-MM1 by the Maser Monitoring Organization (M2O) operating several radio telescopes in the world. The proper motion of G358.93$-$0.03-MM1 was measured to be 1-2 mas (milliarcsecond) Day$^{-1}$ (11,700-23,400 km s$^{-1}$ at $d$ = 6.75 kpc) by VLBI observations of 6.7 GHz methanol masers. Such a fast motion could be explained under the hypothesis of an accretion event in which enhanced far-infrared radiation drives the production of the methanol masers. Last of all, we introduce future prospects in section 4.