  We present the catalog of high Galactic-latitude ($|b|>10^{\circ}$) X-ray
sources detected in the first 37-month data of Monitor of All-sky X-ray Image
(MAXI) / Gas Slit Camera (GSC). To achieve the best sensitivity, we develop a
background model of the GSC that well reproduces the data based on the detailed
on-board calibration. Source detection is performed through image fit with the
Poisson likelihood algorithm. The catalog contains 500 objects detected in the
4--10 keV band with significance of $s_{\rm D, 4-10 keV} \geq 7$. The limiting
sensitivity is $\approx 7.5\times10^{-12}$ ergs cm$^{-2}$ s$^{-1}$ ($\approx
0.6$ mCrab) in the 4--10 keV band for 50% of the survey area, which is the
highest ever achieved as an all-sky survey mission covering this energy band.
We summarize the statistical properties of the catalog and results from cross
matching with the Swift/BAT 70-month catalog, the meta-catalog of X-ray
detected clusters of galaxies, and the MAXI/GSC 7-month catalog. Our catalog
lists the source name (2MAXI), position and its error, detection significances
and fluxes in the 4--10 keV and 3--4 keV bands, their hardness ratio, and basic
information of the likely counterpart available for 296 sources.
