English Address: 1F, No. 46, Lane 51, Sec. 1, Da-An Rd, Taipei City 106, Taiwan
Chinese Address: 106 台北市 大安路一段51巷46號1樓
Google Map to location: Click Here
Phone: +886-2-2740-2428
Facebook: Monster Taipei
The store's original location was in the Ding Hao department store on Zhong Xiao East Road. (Well, technically the owner had a small shop before that on Xin Yi East Road, back in the mid-1990s.) Monster Taipei later expanded to a second nearby location in the mid-2000s. That was called Monster Gear, and it focused on clothing.
Side note: The shop that was previously in the Monster Gear space was called Pixie. It was run by toy designer Mark Chang, who made a cool toy called So What. Taiwan megastar Jay Chou (周杰倫) even designed a version of the toy.
The Monster Taipei Ding Hao location closed in 2014 or 2015, I think. Then Monster Gear and Monster Taipei combined in the Monster Gear location, which I visited recently.
Here's a video I shot of the store: